Activists: Dozens killed in Hama after U.N. visited (AP) BEIRUT - Syrian troops armed with heavy machine guns killed dozens in the central city of Hama Monday, activists said, just a day after chanting protesters welcomed a visit by a U.N. team sent to observe a shaky cease-fire. The day's violence, the city's worst in months, added a dangerous new aspect to the U.N. team's work: that the Syrian regime might exact deadly revenge against opponents who feel empowered by the observers' presence to spill into the streets. Observance of the truce, which was supposed to begin April 12, has been spotty at best. The main manifestation has been a temporary halt to fighting between President Bashar Assad's troops and rebel forces in locations where observers are present. Skepticism about the cease-fire remains high, but world leaders say the current plan to stop more than a year of hostilities might be the last chance. Some details of Monday's events in Hama remained murky, though different activists said the attacks started early in the morning and stopped a few hours later, after dozens had been killed. Rami Abdul-Rahman, the head of the Britain-based Syrian Observatory for Human Rights, said troops stormed the town, firing assault rifles and heavy machine guns, killing at least 33 people. An activist named Ahmed reached by phone in Hama said troops shelled the Arbeen district early Monday before sending in foot soldiers. He said 27 people were killed, and families were still searching damaged homes for others. He did not give his full name for fear of retribution. Another activist in Hama, Mousab Alhamadee, reached via Skype, said as many as 50 had been killed. He guessed the attack was a direct result of the U.N. monitor's visit Monday. "This was the punishment for the people of Hama because yesterday they were very brave when they met the U.N. monitors," he said. U.N. observers tour rebel-held town in Syria U.N. aims to triple Syria observer team next week Syrian soldiers say they're scared, exhausted The U.N. has sent an advance team of eight observers to Syria as part of international envoy Kofi Annan's plan to end the fighting. More monitors are due to arrive in the coming days, and the U.N. has authorized a mission of 300 total observers, though it remains unclear when the full contingent will deploy. Many Syrians, as well as the Western powers, have voiced skepticism about Assad's willingness to abide by the plan for ending the bloodshed and launching talks between the regime and the opposition. They say the Syrian leader is largely paying lip service to the truce, since full compliance - including withdrawing troops and heavy weapons from populated areas and allowing peaceful demonstrations - could quickly sweep him from power. Since the cease-fire went into effect, regime forces have continued to shell rebellious areas, and rebels have attacked regime checkpoints and military convoys. The regime responded with a withering crackdown, which prompted many in the opposition to take up arms to fight government troops. The Syrian state news agency said Monday that "terrorists" killed a doctor in the country's south, two military officers in the central province of Hama and two others in the south.