Pakistani police say militants have attacked one of their stations in the northwestern part of the country, killing at least 10 police officers and wounding five others.

Local police officials said militants armed with guns and grenades attacked a station in the small town of Kolachi Saturday. At least 17 police officers were on duty at the time.

Security forces and the militants clashed for several hours before police were able to retake the station.

The Pakistani Taliban claimed responsibility for the attack, saying the group sent two attackers, one of them a woman. It is still unclear how many attackers were actually involved in the assault. The Taliban has vowed retaliation for the killing of al-Qaida leader Osama bin Laden in Pakistan and routinely attacks security targets.

Kolachi is located near Pakistan's volatile South Waziristan tribal region, a known stronghold for the Pakistani Taliban and an area where authorities are targeting militants.

Earlier Saturday, officials in northwest Pakistan said 15 militants were killed in a clash between rival militant Islamist groups.

Authorities say several people were wounded in the battle in the Orakzai tribal region near the Afghan border. It was not immediately clear what caused the clash.

Meanwhile in the south, officials said a bomb partially exploded outside the Red Cross office in Karachi.

Authorities say two motorcyclists delivered the bomb to the site. Officials say there were no injuries from the small blast.