QUETTA, Pakistan (AP) -- A Taliban car bomb targeting a police vehicle killed 11 policemen and one civilian Thursday in an area of southwest Pakistan wracked by Islamic militancy and a violent separatist insurgency, police said.

The bombing on the outskirts of Quetta, the capital of Baluchistan province, came the same day as fighting in the restive northwest left 4 soldiers dead. Police claimed 20 militants also died in those clashes.

The Quetta blast wounded 23 people, said senior police officer Fayaz Sumbal.

Pakistani Taliban spokesman Ahsanullah Ahsan claimed responsibility for the attack in a telephone call to The Associated Press, saying it was revenge for militants killed in the country's northwest.

The Taliban have been waging a bloody insurgency against the Pakistani government for years that has killed thousands of people. The militants want to impose Islamic law in the country and end the government's unpopular alliance with the United States.

The car was packed with around 100 kilograms (220 pounds) of explosives and was parked alongside a road in the city. It was detonated by remote control when a vehicle carrying members of the police's special forces team passed by, said Sumbal.

Eyewitness Irshad Ali said the blast "was so loud, we thought something had fallen from the sky." Local TV footage showed that the bomb completely destroyed the police vehicle.

The special forces unit that was targeted was put together months ago to deal with increasing incidents of kidnappings and shootings in Baluchistan, said Sumbal.

Also Thursday, several militants attacked a Pakistani army checkpoint in Kurram tribal area near the Afghan border, killing four soldiers, said local police officer Mujahid Khan.

The soldiers, backed by gunship helicopter and jet fighters, chased the militants fleeing to their hideouts and killed 20 of them, he said.

Pakistan's tribal region is home to a wide range of Islamic militants, many of them linked to al-Qaida and the Taliban.

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Associated Press writer Hussain Afzal in Parachinar, Pakistan, contributed to this report.