The bomb attack at the Kandahar Airfield, the main base for the U.S.-led coalition in southern Afghanistan, came hours after suspected Taliban rebels ambushed a police convoy west of Kandahar city, killing two officers and wounding 13 others, police said.
Mirza Khan, a district deputy police chief, said some insurgents were believed killed or wounded during a two-hour gunbattle that ensued after the ambush because pools of blood were found on the ground, but no bodies were found.
Meanwhile, in eastern Khost province, a bomb in a mosque killed senior pro-government cleric Mohammad Khan and wounded 18 others, the latest attack on pro-government Muslim leaders in Afghanistan, said local police chief Mohammad Ayod.
All the tankers were destroyed in the blast before dawn Friday and clouds of black smoke poured over base before the fires were extinguished, officials and eyewitnesses said. Two drivers were injured.
Afghan army commander Gen. Mohammed Sarwar said a bomb was believed to have been hidden in one of the tankers. He said the two injured drivers had been rushed to a hospital.
U.S. military spokeswoman Sgt. Marina Evans confirmed that some fuel tankers had been hit by a blast and had caught fire, but said the tankers belonged to the Afghan army and had been driving past the base when one hit a land mine.
However, an Associated Press reporter saw the blackened remains of the eight tankers in one of the base's parking lots, next to its outer walls.
There has been a string of attacks on tankers contracted by the coalition to haul fuel to its bases from neighboring Pakistan. Friday's was the biggest in months.
The blast came amid a major surge in violence by Taliban-led rebels that has left more than 1,400 people dead in the past half year and raised fears for Afghanistan's nascent democracy.
Violence has risen sharply in and around Kandahar, a former Taliban stronghold, with four suicide bombings in recent weeks and five medical aid workers killed Wednesday as they were returning to the city after treating people at a nearby refugee camp.