Story highlights Police say 7 militants on motorcycles attacked the parked oil tankers Thursday night

The tankers had been parked since Pakistan shut down NATO supply routes last month

Closing the routes was a response to NATO airstrike that killed 24 Pakistani soldiers

No injuries reported in the attacks on tankers; police say the attackers escaped

Militants armed with rocket-propelled grenades and automatic weapons attacked and destroyed at least 22 oil tankers parked in Pakistan, carrying fuel for NATO troops in Afghanistan, a senior Pakistani police official told CNN.

At least seven militants on motorcycles took part in Thursday night's attack, said police official Hamid Shakeel. All seven escaped the scene, he said.

The attack took place at a terminal just outside of Quetta, the capital of Balochistan province, where the trucks had been parked since November 26, Shakeel said.

On November 26, the Pakistani government shut down both NATO supply routes through Pakistan to Afghanistan in protest of a NATO airstrike that had killed 24 Pakistani soldiers earlier in the day.

The airstrike was the latest blow to an already stormy partnership between the United States and Pakistan and plunged relations into perhaps the worst crisis since the two countries agreed to join forces in the fight against Islamist militancy after the 9/11 terrorist attacks.

Roughly 40% of supplies for NATO forces in Afghanistan travel through Pakistan.

During the past two years militants have increasingly targeted NATO tankers and supply trucks in an attempt to disrupt two key supply routes and undermine the NATO mission in neighboring Afghanistan.

The attacks have forced NATO to increasingly use alternative routes through central Asia.

Police said there were no reports of any injuries immediately after the attack.