QUETTA, Pakistan -- Gunmen armed with a rocket torched 29 NATO oil tankers in southwestern Pakistan before dawn Saturday, the latest attack on the supply line for international troops in Afghanistan since Pakistani authorities closed a key border crossing amid a dispute with the United States.

Two responding police officers were wounded.

Local government official Abdul Mateen said Saturday's attack occurred in the area of Mithri, about 120 miles east of Quetta, the capital of Baluchistan province. He said the attackers used guns and fired a rocket to destroy the tankers.

"We are facing problems in extinguishing the fire," he said.

At least 10 gunmen were involved in the attack, police official Jamil Khan said. The oil tankers were parked near a roadside restaurant.

When local police responded, the gunmen fired on them before fleeing. One officer was wounded by a bullet, while another suffered slight burns as he tried to stop the blaze, Mateen said.

Pakistan shuttered the border in Torkham on Sept. 30, following a NATO helicopter strike that killed two Pakistani border guards. Since then, there have been several attacks on supply convoys, including two in which militants torched 70 fuel tankers and killed a driver.

The Pakistani Taliban have claimed responsibility for such previous attacks and have demanded that the government permanently bar NATO and the U.S. from using its soil to transport supplies to Afghanistan.

The U.S. has apologized for the cross-border helicopter strike, but Islamabad has yet to open the border crossing at Torkham. Still, officials believe it could be reopened next week. A smaller crossing in the southwest has stayed open.