2 Blasts Hit University in Pakistani Capital

Pakistani officials say two bomb blasts have killed at least four people and wounded several others at the International Islamic University in the capital city.

Police are working to confirm reports that the blasts were carried out by two suicide bombers. Television footage showed security forces sealing off buildings pockmarked by shrapnel.

No group has claimed responsibility, but Pakistan's interior minister reacted to the blasts by saying all terrorist attacks in Pakistan lead back to South Waziristan.

Many schools in Pakistan closed this week, fearing retaliatory attacks stemming from the army's new offensive against Taliban militants in South Waziristan.

Pakistani troops continued to battle militants Tuesday on the fourth day of the offensive. Officers claimed troops killed some 20 militants during overnight fighting. The deaths would bring the total number of suspected militants killed to nearly 100 since the operation began Saturday.

Officials said troops fought Tuesday to try to gain control of the key town of Kotkai. The army claimed ground troops backed by air support seized control of nearby mountaintops Monday, but have not yet taken the town.

There is no independent confirmation of the army's or the militants' accounts of the fighting because no journalists are traveling with the Pakistani military and the region is extremely dangerous for outsiders.

The U.S. defense secretary said Tuesday that he has been "encouraged" by the offensive although it is just a few days old. Robert GatesRobert Gates told reporters that recent terrorist attacks in Pakistan make clear the need to deal with the militant problem.

Officials say more than 100,000 civilians fled South Waziristan before the assault, and thousands more left their homes in the past three days.

Pakistani army commanders say about 30,000 troops are battling about 10,000 militants, including foreigners. Authorities blame the extremists for a wave of attacks across the country in recent years, including assaults in the past two weeks that have killed more than 175 people.

Pakistani military officials say they expect the South Waziristan offensive to last six to eight weeks, before winter weather makes fighting difficult.