Rockets have hit a protest camp in Yemen’s capital, Sana’a, killing at least two people on a third day of violence that continued the government’s deadliest crackdown yet on pro-democracy demonstrations.

Heavy shelling and machine-gun fire rocked the city early on Tuesday morning, marking an escalation in Yemen’s eight-month standoff between troops loyal to President Ali Abdullah Saleh and protesters backed by soldiers who have defected to the opposition.

Witnesses told Reuters at least three missiles struck the camp just after morning prayers at around 5am local time. “The rockets hit some of the men who were walking outside past a market. I have two dead and five hurt,” said Dr Mohammed al-Qubati, the director of a field hospital at the protest camp on a site the protesters have dubbed Change Square.

“We were walking back from prayers. All of a sudden a rocket hit close by from out of nowhere and some people fell down. And then a second one came and that’s when we saw the two martyred,” said Manea al-Matari, a protest organiser camped in the square.

No one from the government was immediately available to comment on the reports. Officials on Monday said government soldiers were not targeting protesters and blamed the bloodshed on the opposition.

At least 56 people were killed on Sunday and Monday, said doctors and witnesses, after demonstrators demanding an end to Saleh’s 33-year rule stepped up their protests.

Government forces responded to the demonstrations with heavy fire, while snipers shot at activists from rooftops.