An Al Qaeda suspect killed two police guards Sunday in an unsuccessful attempt to escape from custody in a Yemeni hospital, medical staff said.

The suspected militant grabbed the weapons of two of his guards and killed them. He then exchanged fire with the three remaining guards, according to staff at the Republican Hospital.

"Smoke was seen coming out of his room" and he handed himself in, a hospital official said.

A source close to the police who requested not to be named said the suspect was believed to have joint U.S.-Yemeni citizenship.

Yemeni authorities intensified their campaign against the country's Al Qaeda branch after it claimed a thwarted Christmas Day bombing attempt on a U.S. passenger plane en route to Detroit.

On Thursday, a security official said 11 men were arrested in the capital Sanaa on suspicion of plotting attacks for Al Qaeda.

Al Qaeda militants targeted various Western embassies in the city in the past.