A suicide bomber hit a car carrying the army's surgeon general along a busy road south of the capital Islamabad Monday, killing him and at least seven others, the army said.
In the north, gunmen opened fire and threw grenades inside the office of the British-based aid group, killing four local staff, the group and police said.
Lt. Gen. Mushtaq Ahmed Baig appeared to be the highest-ranking military official to have died in an attack since President Pervez Musharraf sided with the U.S. after September 11.
Suicide bombers have struck repeatedly over recent months in Rawalpindi, a city just south of the capital where the military has its headquarters. Most of the bombings have targeted security forces but a gun and suicide bomb attack killed opposition leader Benazir Bhutto in the city on Dec. 27.
The latest attack is likely to revive concern about Islamic militancy in Pakistan just days after the opposition won parliamentary elections.
Baig, his driver and his guard were killed along with five civilians, the army said. City police chief Saud Aziz told reporters at the scene that a black car whose roof was ripped off by the blast and dumped on the grassy median belonged to the army.
Dozens of troops and plainclothes security officials cordoned off the area, where at least six other cars lay damaged. Investigators wearing gloves gingerly gathered debris, including pieces of flesh, and put them in plastic bags.
Iqbal Ali, who had been walking toward a nearby government office to get an identity card, said he saw a man run into the road shortly before the explosion.
In northern Pakistan, up to 12 assailants entered the office of British-based aid group Plan International in the town of Mansehra and opened fired indiscriminately before setting off three explosions. Four local staff members died and the office was burned to the ground, the group and local officials said.
Muhammad Niaz, a senior doctor at Mansehra's hospital, said eight people were injured.
The identity and motive of the attackers were not immediately clear. Mansehra lies about 50 miles north of Islamabad and is not an area associated with the Islamic militancy in areas farther west.
Police official Attaullah Wazir said officers had chased the attackers into a local forest and that the two sides were exchanging gunfire.
Plan International, which focuses on the welfare of children, said it would halt its operations in Pakistan. The aid group said it had worked in Mansehra for more than a decade. It was involved in providing relief to people affected by the massive 2005 earthquake in northern Pakistan.
The fresh eruption of violence came a day after Taliban-style militants battling government forces near the Afghan border said they want dialogue with the winners of the elections and urged the new leadership to abandon the war on terror.
Bhutto's party finished first in last Monday's parliamentary elections, while supporters of Musharraf were trounced. However, all major political leaders have said they are committed to fighting extremism.
In the wake of the opposition victory, some Pakistani leaders and many media commentators have called on Musharraf to resign.
The Bush administration appears to want Musharraf to continue in office. However, several U.S. senators met who Musharraf after the vote said Sunday he should seek a "graceful" exit from power.
Musharraf's spokesman dismissed the suggestions on Monday.
Musharraf was elected to a new five-year presidential term last year by Pakistani lawmakers, "not by any senator from the United States," his spokesman Rashid Qureshi told Dawn News television. "So I don't think he needs to respond to anything that is said by these people."
Western officials are concerned that an attempt to force Musharraf from power would spark a constitutional crisis and hobble Pakistan's effort to fight growing Islamic extremism.
The parties of Bhutto and another former premier, Nawaz Sharif are expected to form a coalition government. However, they fell short of the two-thirds majority needed to impeach Musharraf, whose popularity plummeted last year after he declared a state of emergency and clamped down on the opposition, the judiciary and the media.