AP/ January 9, 2012, 12:50 PM

Syria protesters fired on as observers visit

Arab League observers arrive at a Greek Orthodox church in Damascus on January 9, 2012 to attend a mass held in memory of a 10-year-old Christian boy (killed last month in Homs as he ventured out to buy cookies) and the son of Syria's Grand Mufti Ahmad Badreddin Hassoun, who was also killed in the flashpoint city in October. / JOSEPH EID/AFP/Getty Images

BEIRUT — Syrian troops fired on protesters Monday in the restive city of Homs as Arab League observers toured the area to see whether President Bashar Assad's regime is abiding by its pledge to halt the 10-month-old crackdown on dissent, activists said.

In the capital Damascus, thousands held prayers for those killed since the uprising began in March. Christian and Muslim religious leaders attended the service, and throngs packed the city's Holy Cross church, its yards and a nearby street.

"Enough killings in our beloved Syria," the country's top Sunni clergyman, Grand Mufti Ahmad Badreddine Hassoun, told the crowd at the prayer service. His son was shot dead in October.

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The 165 foreign monitors are supposed to be ensuring that Syria complies with the Arab League plan stipulating the regime stop killing protesters, remove heavy weaponry, such as tanks, from all cities, free all political prisoners and allow in human rights organizations and foreign journalists. Syria agreed to the plan on Dec. 19.

However, the crackdown has not stopped and opposition activists say around 450 people have killed by the regime since observers began work on Dec. 21. On Monday, the British-based Syrian Observatory for Human Rights said security forces shot dead four people around the country and returned the bodies of 10 other people to their families in several Homs neighborhoods.

The U.N. estimated several weeks ago that more than 5,000 people have been killed in political violence since March. Since that report, opposition activists say hundreds more have died.

On Sunday, the Arab League repeated its demand for the Syrian government to immediately stop all bloodshed.

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It was not immediately clear whether the foreign observers witnessed the regime forces opening fire in the Khaldiyeh neighborhood of Homs. Several people were reported wounded.

Majd Amer, an activist in Homs, said the shooting started after thousands of protesters surrounded a group of observers, urging them to go to Khaldiyeh, where anti-regime protesters are known to be active. The observers' Syrian escorts wanted to take them to the nearby Abbassiyah neighborhood, where many regime supporters live, he said.

"Sporadic shooting was heard for a few seconds," Amer said.

The opposition has accused Syria of trying to mislead the activists by showing them areas where regime support is strong.