Harrowing Red Cross video shows responders rushing to help Westgate mall victims as questions remain over Kenya's handling of the attack The video shows seriously wounded people wailing and calling out for help At least 67 people were killed in the attack, with many unaccounted for There is speculation that the Kenyan military may have killed some civilians A 24-hour candlelight vigil has been held for victims of the massacre A harrowing video filmed by the Kenyan Red Cross shows responders rushing to help the injured shortly after the assault on the Westgate mall began. The footage, obtained by The Associated Press, shows rescuers entering the Nairobi's mall's upper level parking area on September 31 and treating the injured as bodies lie on the pavement. The end of the graphic video appears to show several seriously wounded and dead people where a children's cooking event had been taking place. Injured people are wailing and calling out for help. Harrowing: The Kenyan Red Cross treats the injured from the mall attack Bloodbath: Paramedics tended to the injured as the gunmen continued to roam the mall A sixth Briton has been confirmed dead following the atrocity, the Foreign Office said today. Earlier this week Prime Minister David Cameron suggested six Britons may have died in the catastrophe and the Foreign Office confirmed this figure on Saturday. The person's identity has not been revealed. A spokesman said: 'FCO can confirm a sixth British national has been identified amongst those killed in the tragedy in Nairobi. We have no information at this time that any further British nationals have been killed although we cannot rule out the potential for further British casualties and we continue to stay in close contact with the Kenyan authorities as their investigations continue. The video comes as hundreds of mourners and security personnel have held a 24-hour candlelight vigil for victims of the massacre. Inside the mall on Friday - the last of three days of an official mourning period - a pushchair could be seen overturned on the marble floor next to wilting fresh flowers at a florist's shop. Slabs of concrete sat on top of flattened cars in the parking area. Elsewhere, there were rows of scorched vehicles. Earlier, a top official said Kenya's military caused the collapse of three floors of the mall in the deadly terrorist siege as the government urged patience with the pace of an investigation that has left key questions unanswered. Seven days after 67 people were killed in the attack on the upmarket shopping centre, there is still no clear word on the fate of dozens who have been reported missing and no details on the terrorists who carried it out. Atrocity: A woman who had been hiding during the gun battle runs for cover after armed police enter the Westgate Mall in Nairobi Aftermath: Kenyan security personnel direct traffic after the main road next to the Westgate Mall was reopened, in Nairobi, Kenya on Saturday The account of the roof collapse raises the possibility that the military may have caused the death of hostages in its rescue attempt. An undisclosed number of people are feared to be buried in the rubble. The official said post-mortem examinations would be conducted on any bodies found - from the militants or the structural collapse. The official also said Kenyan troops fired rocket-propelled grenades inside the mall, but would not say what caused the floors to collapse, if the action was intentional, or if it was an accident. The account at least partially backs up information given on Wednesday by another official who said RPGs fired by soldiers created a gaping hole in the mall's roof and caused the floors to collapse. Devastation: The collapsed upper car park of the Westgate mall in Nairobi Four huge explosions rocked the mall on Monday and dark smoke poured out - the likely time that the floors collapsed. The government has not said publicly what caused the collapse. One official had earlier suggested it was caused by a mattress fire in the Nakumatt department store. Presidential spokesman Manoah Esipisu said structural engineers were examining the collapse. FBI agents, along with investigators from Britain, Canada and Germany, are taking part in the inquiry. Results are not expected until next week at the earliest. Protest: Somali women listen to a speaker at a solidarity rally to denounce al Shabaab's attack of a shopping mall in Nairobi, in Minneapolis, Minnesota The Daily Nation newspaper reported that the initial counter-attack against Al-shabab was made by the police and local vigilante groups, who managed to corner the terrorists. But further progress was hampered by the police commander being accidentally shot dead by troops, who arrived on the scene shortly afterwards. Police are trying to determine if the attackers stored ammunition in the mall hours or even days before the attack, and investigators are tracing the ownership of a car that has been discovered and is believed to have been used by the gunmen. Al-Shabab said it carried out last Saturday's attack to punish Kenya for sending its troops into Somalia to fight the al Qaida-linked militant group that had seized large parts of that country for years before being dislodged from the capital Mogadishu. Eight suspects are being held over the attack, interior minister Joseph Ole Lenku said. Three others who had been detained were released. The government says at least 61 civilians and six security forces were killed. At least five attackers were also killed. Under siege: Heavy smoke rises from the Westgate mall in Nairobi on Monday September 23 At the request of Kenya, Interpol issued a notice asking for help in capturing 29-year-old British-born fugitive Samantha Lewthwaite - not in connection with the mall attack, but over a 2011 plot to bomb holiday resorts in Kenya. Known as "the white widow," she was married to one of the suicide bombers in the July 7 2005 attack on London's transport system, and there is speculation that she was involved in the mall attack. But Mr Lenku suggested that Interpol raised the issue of the international alert. He declined to discuss any links to the mall attack, saying he "wouldn't want to pre-empt the position of the forensic investigation taking place." Kenyan officials have offered at times contradictory accounts of the siege and are reluctant to release many details of the investigation prematurely. Mr Lenku urged patience, saying the investigation is "a very delicate and complex operation that requires time." He said no bodies had been recovered from the rubble and no official reports of missing persons had been filed. The Kenyan Red Cross has said 59 people are unaccounted for, raising fears of bodies in the debris. The possibility that government troops were behind the roof collapse only added to the frustrations of Kenyans questioning what happened at the mall. "You have to blame the government, not the soldiers, because they had to get their orders from somewhere," said John Odera, a security guard. They should be held responsible for what they did. A user-generated list of more than 80 questions on social media includes "How many terrorists were involved in the attack?," "Are any terrorists loose in the city?," "Can we see the bodies of the 'neutralised' terrorists?" and "Are we still safe?"