Ramadi, Iraq, Dec 1 (SPA) -- Iraqi rebels attacked a U.S. base and a local government building with mortar rounds and rockets in Ramadi, west of Baghdad, on Thursday, before holding ground on several central streets, residents said. Around 400 heavily armed, masked men were patrolling the main thoroughfares of the city, long a focus of guerrilla activity, and had set up checkpoints at major entrance and exit points, residents from across Ramadi told Reuters. "They've taken control of all the main streets and other sections of Ramadi," a reporter there for Reuters said. "I've seen about 400 armed men controlling streets, some of which were controlled by Americans before," he said. The assault began early on Thursday with a sustained mortar and rocket attack on a U.S. base in the city centre and on a nearby provincial governor's building. Ramadi is the capital of Anbar province, a heartland of the insurgency. The U.S. military did not immediately respond to a request for information about the situation. --SPA1242 Local Time 0942 GMT www.spa.gov.sa/306945