LAHORE, Pakistan (CNN) -- Two bomb blasts killed at least 21 people and wounded 74 in Rawalpindi -- a city next to Islamabad -- Tuesday morning, Pakistani police and hospital sources said.
Security officials examine the damaged bus at the site of the bomb blast in Rawalpindi, Pakistan, Tuesday.
One of the explosions was caused by a bomb hidden on a bus carrying government employees, police said.
There were few details available concerning a second bomb that exploded in Rawalpindi at about the same time.
The number of dead and wounded in each bombing was not immediately clear, but police and hospital officials said the combined death toll was 21 along with 74 hurt.
No one immediately claimed responsibility for the attacks, police said.
Pakistan, a key ally of the United States in its war on terror, has been hit by numerous bomb attacks this year.
At least 49 people were killed in bomb attacks across the country on July 19 alone.
Militants linked to the Taliban in the area near the Afghan border say a truce reached with the Pakistani government last September is off.
That deal has been blamed for an increase in attacks on U.S. troops over the border in Afghanistan, as Taliban fighters were able to prepare, train, and reconstitute weapons supplies without interference from the Pakistani government.
But Pakistani and U.S. intelligence officials worry about what happens if the cease-fire isn't salvaged. They fear the militants could spread their attacks to Pakistani cities, potentially developing a wider home base in Pakistan, a country that has nuclear weapons.
The Pakistani government has sent tribal elders to meet with militant leaders in the area in hopes of reviving the peace deal.
The Taliban are the former Afghan regime that sheltered al Qaeda until the U.S.-led war following the September 11, 2001, attacks. Now, U.S. intelligence officials say al Qaeda has established a "safe haven" in Waziristan, just over the border into Pakistan, and that Osama bin Laden is believed to be in the area.
Pakistan President General Pervez Musharraf has cracked down on al Qaeda militants and arrested many, including in the Waziristan area before the truce was reached. But his critics say he has failed to prevent the terrorist group from growing inside his nation's borders. E-mail to a friend
CNN's Mohsin Naqvi in Lahore contributed to this report.