Activists: 3 Syrian intelligence officers killed in capital city of Damascus Updated at 5:02 a.m. (AP) BEIRUT - Three Syrian intelligence officers were killed in Damascus on Tuesday, activists said, the latest attack on regime targets as the country's 13-month conflict grows increasingly militarized. The attack took place as a U.N. team observing Syria's violence-ridden truce was visiting another area near the capital, the restive suburb of Douma. Activists and amateur videos reported that the area was being shelled. The Britain-based Syrian Observatory for Human Rights said the three officers were killed early Tuesday in the Barzeh neighborhood but gave no further information. The Syrian government did not comment. Rebels seeking to topple President Bashar Assad have ramped up attacks on military targets and security officers, some of whom have been killed in their cars on the way to work. The U.N. says more than 9,000 people have been killed since the conflict began in March 2011 with mostly peaceful protests calling for political reforms. The government brutally cracked down, deploying troops, snipers and pro-government thugs to quash dissent, while many in the opposition have armed themselves for protection. The international community remains divided on how to stop the conflict, with the U.S. and many Western nations calling for Assad to leave power while Russia and China have stood by Damascus. All, however, have endorsed a six-point plan by envoy Kofi Annan that calls for a cease-fire to allow for talks between all sides on a political solution to the conflict. Despite broad backing, the plan has been deeply troubled since the cease-fire was to go into effect on April 12. The Syrian government has not withdrawn its troops from populated areas or allowed media access and its troops have shelled opposition areas. Armed rebels, too, have continued to attack military convoys and checkpoints. The regime cites such attacks in arguing that the uprising is the work of armed terrorists acting out a foreign conspiracy to weaken the country. An 11-person monitoring team is currently in Syria to observe the cease-fire and prepare for a total team of 300 monitors to arrive later. But some areas that have welcomed the team with anti-government demonstrations have faced apparent retribution from the regime. On Monday, more than 30 people were killed in the central city of Hama, just one day after the monitoring team visited the city. One amateur video posted online showed blood in the streets. Another showed 15 bodies laid out in rows and wrapped in white cloth. The Observatory said 55 people were killed across Syria on Monday. Syria's state news agency said U.N. observers were visiting the restive suburb of Douma Tuesday, their second visit in two days. A Douma activist, Mohammed Saeed, said via Skype that he had heard the observers arrived but had no information on their visit. "The news here is very bad," he said. "There are tanks and shelling and gunfire and the army has prevented fire engines from entering the city," he said. Amateur videos posted online showed an explosion in the area and smoke rising into the sky.