On the January 9, 2007, American and Iraqi forces began a joint operation. The US 1st Battalion of the 23rd Infantry Regiment under the command and control of Colonel (Brigadier General) Bryan T. Roberts, Commander, 2nd Black Jack Brigade, 1st Cavalry Division, linked up with Iraqi forces on the north end of Haifa street and began occupying buildings and arresting suspects. At 7:00am hundreds of insurgents started to shoot at the Americans from the high-rises (the Holland Apartments). Heavy incoming fire pinned down the American soldiers trapping them on a rooftop for at least two hours. Some soldiers who were not on the rooftop could not move on the street because of sniper and machine-gun fire. The fighting became so intense that US Apache helicopters, F-15E Strike Eagles, more than a dozen Iraqi gun trucks, Stryker combat vehicles and about 1,000 Iraqi Army soldiers were called in.