BEIRUT, Lebanon — Syrian security forces killed at least 15 people on Tuesday in the central city of Homs, residents and activists said, in a violent escalation in a place that has emerged as a focal point of the uprising against President Bashar al-Assad.

Armed men loyal to the government opened fire as funeral processions for 10 protesters who were killed Monday left the Khaled Bin al-Waleed mosque. Among those who died were the mother and the son of a demonstrator killed Monday, said an activist in the Homs neighborhood of Bab Amr who identified himself as Mohammad and was reached by telephone.

“The security forces started shooting at the funeral processions, then people ran for cover, some hiding behind the mosque, others behind parked cars,” he said. “An army tank then ran over cars, smashing seven.”

The killings in Homs, 100 miles from Damascus and in one of the country’s poorest regions, followed a wave of sectarian bloodshed over the weekend in which six people died. Three of the victims were from the minority Alawite sect, an offshoot of Islam, and their corpses were mutilated and thrown in a deserted area outside the city. The discovery of the bodies enraged other Alawites who rampaged, killing three Sunni Muslims and vandalizing and setting fire to dozens of shops owned by Sunnis.