Pakistani officials say the death toll from a suicide car bombing Tuesday in the central town of Dera Ghazi Khan has risen to at least 27.
Investigators say dozens of people have been injured in the blast, with some victims possibly trapped under rubble.
The explosion occurred in a busy market near the home of a provincial government adviser, Zulfikar Khosa. Officials say several buildings -- including the adviser's home -- were heavily damaged. However, no one was in the home when the attack occurred, and authorities are uncertain if the adviser was the target.
The attack is the latest in a series of bombings that have killed more than 500 people in Pakistan since October.
Officials say militants are retaliating for an army offensive against the Pakistani Taliban in the South Waziristan tribal region.
Meanwhile, Pakistani officials say a court has granted police another 10 days to question five young Americans arrested in Punjab province last week.
On Monday, Pakistan's top court ruled the five men arrested on suspicion of trying to join militant Islamist groups could not be deported until judges review their case.
Sargodha police say the men used Internet sites to try to contact militants in Pakistan before traveling to Pakistan from the U.S. in late November.