Yemeni capital Sanaa was hit by big blasts on early Thursday as the fighting to bring down the current president, Ali Abdullah Saleh, has turned out to be a civil war, Reuters reported.

Reports said that over 40 people have been killed since Monday in northern Sanaa, the place where the supporters of the powerful tribal leader Sadiq al-Ahmar are keep on attacking and trying to take over government buildings.

The explosions can be heard across town in the south of Sanaa. This seems to be heavier weapons than the machineguns and the mortars of the past few days, one resident said, Reuters reported.

The fighting started a day after Saleh pulled out for the third time from a Gulf Arab-brokered deal for him to step down and make way for a national unity government, the report said.

The protesters were got inspired by revolutions in Tunisia and Egypt, and started camping in squares and marching in great numbers demanding Saleh to step down. On the other hand, Saleh's attempts to stop the protests by force cost lives in hundreds.

Many people have left the city to avoid the war.   It's no longer possible to stay in Sanaa. The confrontations will reach all parts of the city, a citizen told Reuters as he left by car.

The supporters of Ahmar, said witnesses have controlled several ministry buildings near Ahmar's compound including the trade and tourism ministries. They have also captured the offices of the state news agency Saba.

Ahmar's supporters also attacked the main building of the Interior Ministry with rocket-propelled grenades, said witnesses.