The 19-year-old, named locally as Moses Yitzchok Greenfeld (above) from Stamford hill, London, was pulled from the water in Hampstead Heath, north London, after getting into difficulty while swimming . Police officers 'watched' as a group of teenagers desperately tried to save their friend who drowned in Hampstead Heath pond, it has been claimed. Moses Yitzchok Greenfeld, 19, from Stamford Hill, London, had been swimming with four friends as temperatures reached 25C when he got into difficulty. An eyewitness has said at least seven police officers stood on a bank and watched as the boys dived in and out looking for their friend. The teenagers were reportedly heard shouting to ambulance crews on the side, asking how long someone could survive under water as they scrambled around trying to save their friend. It is thought Mr Greenfield may have had a cardiac arrest because of the shock of jumping into the cold water. His body was eventually discovered five foot below the surface and 20ft from the water's edge just before 11pm on Wednesday - nearly six hours after he was reported in trouble at 5.30pm. James Eisen, a 43-year-old freelance journalist, said: 'I was walking past and I could see a lot of commotion going on over the far side of the pond. 'The guy's friends were going in and out of the water and holding their breath and diving under frantically. 'There were police officers and paramedics and firefighters on the bank just standing there watching while the boys dived under. There was at least seven police officers on the side. 'It was a chaotic and surreal scene. 'I heard one of the boys shouting to one of the ambulance crews and asking how long someone could survive under water without breathing as they continued swimming around in a panic. 'I'm guessing the emergency services are told not to go into the water but if that's the case they probably shouldn't have let the boys carry on swimming about. 'Before I left the police helicopter was flying over and they had launched some boats onto the pond.' Mr Grunfeld's family have paid tribute to the teenager, who they described as a 'wonderful' and 'friendly' man, but said there was no blame because they believed that was the way God was meant to 'take him.' Mr Greenfeld, who is from the Orthodox Jewish community and is thought to have lost his Rabbi father to cancer five years ago, had recently flown home to London from New York, where he was studying religion at a Jewish college. Tragically, he only returned the UK to be with his family during the Passover holiday. His sister, who asked not be named, said: 'He was a wonderful young man and lovely brother who was very well liked, friendly, and he will be dearly missed by his family and friends. 'He was very into studies but he was very fun to be with and he would always try to lend a hand.” Police, specialist divers and 30 firefighters scoured the water for the missing teenager and his body was found five foot below the surface just before 11pm last night. He got into difficulty while swimming with four friends . 'We believe that whatever God does is for the good, so if that’s the way he [God] was meant to take him [Moses] then it must be good for him and for us, because it was meant to be. 'So there’s no blame, no pointing, because what was meant to happen, happened, and there was nothing anybody could have done to avoid it.' Speaking of the police response she added: 'Of course we would have liked it if they could have got their quicker. But we really appreciate what the police have done and they treated us and our religious beliefs with respect. 'They waited for Jewish men to come [to the pond] to handle the body, and we really appreciate that.' The group had been swimming outside of the designated area and out of hours at a time when no lifeguards were on duty, it was claimed. Members of his family gathered at the edge of the large pond – which had been packed in the day with sunbathers – as specialist divers from the Marine Policing Unit and around 30 firefighters scoured the water for him. Emergency services workers could be seen taking a stretcher into the park after the discovery of the body . The tragedy came on the hottest day of the year so far as temperatures reached 25.1C at St James's Park in the capital and in Frittenden, Kent. It is believed Mr Greenfeld may have suffered a heart attack brought on by the sudden change in body temperature after diving into the chilly 8C  pond, the Evening Standard reported. A friend of Mr Greenfeld told the newspaper: 'He arrived with pals after driving up from Hackney. They got here after 5pm and the lifeguard was not on duty. 'I think Moses got into difficulty in the shallow part of the pond but there's a steep drop-off. They recovered his clothes from the side of the pond. 'His mother is devastated. He lost his father to cancer when he was young.' The boys had entered the water after the 4.30pm closure wearing what Mr Eisen described as boxers or swimming shorts. He was seen scrambling in a 10ft deep section of the pond and shouting for help before he disappeared under the surface. Emergency services were called just after 5.30pm and a subsequent search involved 30 firefighters, a police marine unit and a police helicopter. The young man's body was eventually pulled out at about 11pm after extensive searches of the murky water. The heath is controlled by the Corporation of London and a spokesman said that officers had not entered the water to try and save the drowning teenager. Last night, members of Mr Grenfeld's family gathered at the edge of the large pond – which had been packed in the day with sunbathers – as specialist police divers and around 30 firefighters scoured the water for him . Members of the Hatzola team, a group which provides 24/7 emergency care and ambulance services in London, were also called to the scene, along with a police helicopter, specialist divers and about 30 firefighters . A spokesman said: 'The heath constabulary officers are here to enforce bylaws in the park, they are not trained lifeguards and the water is dangerous and very murky, so they are advised they are not to go in until proper assistance arrives. 'He was swimming away from the designated area and out of hours so there were no lifeguards on duty. 'There are signs everywhere warning people not to go into the water at these times. 'Visibility in the water is about six inches, it's very murky, and you can barely see in front of your face. 'He had swum out over a ten foot drop and was about 20 feet from the side when he experienced difficulty - you have to be a strong swimmer to be out there. 'It is a complete tragedy but these are the facts behind it.' The Metropolitan Police confirmed a report was now being prepared for the coroner. The heath was full of sunbathers as the incident unfolded yesterday, as dozens of people had gathered to enjoy the unseasonably warm weather. One man, who claimed to be Mr Grenfeld's uncle, said the teenager had gone swimming with friends. He said: 'He went swimming and he must have struggled and he cannot be found. It's very tragic. They did the surface search and they called it off. The divers are coming in. That will change it from a rescue to a recovery.' Henna Anaya, who was on the heath with her son at the time of the incident, said: 'There were about four friends, all of them in the water, and they were swimming. I told my son they were just messing around. 'The next minute someone said to me he was going down and waving his arm and telling his friend to help, he was sinking. There were guys jumping in to help. The guy who went in told me that police had asked him to get out of the water.' Specialist police divers and around 30 firefighters joined the search for a 19-year-old man who got into difficulty while swimming in Hampstead Ponds in Hampstead Heath, north London, yesterday afternoon . Police were initially called to the scene just after 5.30pm after receiving reports from concerned members of the public that a teenager was in difficulty and under the water. His body was retrieved fromt the lake at 11pm . Another witness, who didn't wish to be named, said: 'It was right at the other end from where the lifeguard would have been, so by the time he was struggling, it would've already been too late. 'One woman said she heard the boys shouting for help, but only realised afterwards because at the time she couldn't understand what they were saying. 'The emergency services arrived very quickly, but you can't make miracles. It's just a tragedy.' Andrew Dutton-Parish, a regular swimmer at the Men's Pond who was also at the heath, added: 'It's such a sad start to the summer. It's very rare for anyone to be drowned.' A London Ambulance Service spokesperson said paramedics arrived on the scene within eight minutes, but the emergency teams, accompanied by a police helicopter, were unable to save the young man. The teenager is the second person to have died while swimming on the heath in the past two years. In August 2013, photographer Sussie Ahlburg, 51, from Holborn, drowned in the ladies' bathing pond. It later emerged she had a heart condition and had been warned not to swim in 'open water' by a cardiologist. Hampstead Heath has three swimming ponds which can become extremely busy in good weather. Despite temperatures reaching 25C in London yesterday, waters remained cool on the heath, with temperatures recorded at about 8C. Hampstead Ponds in Hampstead Heath, north London (pictured), is a popular spot for residents and tourists .
Moses Yitzchok Greenfeld died while swimming in Hampstead .
He was seen in difficulty in water at 5.30pm and body recovered at 11pm .
Eyewitnesses claim emergency services crew watched as boys dived in .
Family pay tribute to 'wonderful' and 'friendly' teenager .