A suicide bomber blew himself up outside the gates of a US base in eastern Afghanistan on Monday, killing nine Afghan civilians and wounding 13, officials said. The blast came as the top US official in eastern Afghanistan, Maj. Gen. Jeffrey J. Schloesser, warned that militants would attack military, civilian and government targets during Afghanistan's Independence Day celebrations. The bomber in Khost province rammed his explosives-laden vehicle at the gates of the American military base in Khost city, said Arsallah Jamal, the province's governor. The attack did not penetrate the base's perimeter, the US military said. All victims were civilian, Jamal said. He added that a second bomber tried to ram the police who were investigating the first blast, but was shot dead by officers. US troops provided medical care to the wounded, the US-led coalition stated.