The US embassy in Sanaa, the Yemeni capital, has been attacked by a suicide bomber and armed fighters, witnesses have told Al Jazeera.

 

A suicide bomber on Wednesday morning drove a car close to the embassy before detonating his explosives, witnesses said, leaving part of the building on fire.

 

Armed men then attacked the embassy from a second car, they said. There is no immediate word on casualties from the incident.

 

A US embassy official declined to comment on the blasts. "I cannot confirm it. I cannot talk about it," the official said.

 

A vehicle was on fire on the road past the embassy compound's perimeter and police have sealed off the area, witnesses said.

 

Roads leading to the embassy were closed after the attack and ambulances were seen attending.

 

The US state department in April ordered all non-essential diplomatic staff to leave the country after an attack on the embassy claimed by al-Qaeda the previous month.

 

A residential compound used by US oil workers in Sanaa also came under attack from rockets.

 

The embassy called on Americans in Yemen to "exercise caution and take prudent security measures, including maintaining a high level of vigilance, avoiding crowds and demonstrations, keeping a low profile, varying times and routes for all travel".