A senior U.S. official says the defection of Syria's prime minister shows that President Bashar al-Assad's government “is crumbling.”

State Department deputy spokesman Patrick Ventrell on Monday welcomed Riad Hijab's defection, just two months after taking the prime minister post.

In a statement read in his name on Al Jazeera television Monday, Riad Hijab said he was leaving what he called “the killing and terrorist regime” and joining the opposition.

Jordanian officials said he had defected to Jordan.

Syrian state television said Mr. Hijab was fired and replaced by his deputy, Omar Ghalawanji.

The news came hours after state media said a bomb exploded at the state television building in Damascus, wounding several people. The station remained on the air following the blast, which ripped through the third floor of the building.

A pro-government, private TV station, which itself was hit with a deadly blast in June, broadcast images of the building's damaged walls, wires dangling from a collapsed ceiling and people walking through smoke-filled hallways.

Syrian opposition activists are reporting continued attacks by government forces in the northern city of Aleppo Monday.

The Syrian Observatory for Human Rights says the army is shelling several neighborhoods in Aleppo, and that nationwide nearly 30 civilians had been killed.

Government and opposition claims in Syria are difficult to verify because journalists do not have a freedom of movement.