A suicide car bomber struck a security post in northwestern Pakistan, killing at least nine people and wounding more than 30 others. The attack came hours after suspected Taliban militants in the same region killed two truck drivers transporting supplies for NATO and U.S forces in neighboring Afghanistan. Meanwhile, police in the southern city of Karachi say that three days of ethnically motivated violence has killed at least 17 people and wounded more than 60. From Islamabad, Ayaz Gul reports.

Pakistani military officials and witnesses say that a suicide bomber prematurely detonated his car while trying to bypass the line at a security checkpoint in the violence-plagued valley of Swat.

The powerful explosion caused most of the deaths instantly and damaged several vehicles lined up for a security check. Officials say that a majority of those killed and wounded were civilians.

Pakistani troops have been engaged in anti-insurgency operations in the militant-infested valley.  Actions that have provoked suspected Taliban extremists to retaliate with frequent attacks on security forces and government officials.

Monday's suicide bombing took place hours after dozens of heavily armed Taliban militants attacked a shipping terminal in the northwestern city of Peshawar where trucks loaded with supplies for NATO and U.S forces in Afghanistan were parked.

The militants set the vehicles on fire and killed two drivers before fleeing the scene.

Meanwhile, authorities in Karachi say that there is no let up in violence between the city's Urdu-speaking community known as mohajirs and ethnic Pashtun settlers. After Sunday's violent clashes, all schools and colleges in Pakistan's commercial capital were closed and few people were using public transport on Monday.

Tensions have been running high in Karachi since a major political party representing the Urdu-speaking population began to allege that Taliban militants are gaining strength in Pashtun dominated parts of the southern Pakistani city. But provincial minister Zulfiqar Mirza denies these allegations as "rumor mongering"

"My message for the people of Karachi is that please be peaceful and do not give your year to rumor mongers," he said.

The minister told the provincial legislative assembly that he has ordered the police to shoot trouble-makers on sight to discourage the violence.