ISLAMABAD - A roadside bomb targeting a security vehicle killed three army officers and an enlisted soldier in a troubled northwestern district bordering Afghanistan on Friday, the military said.

In a statement, it said four soldiers were also wounded in the attack in North Waziristan, a former stronghold of Taliban in Khyber Pakhtunkhwa province where army has carried out several operations against local and foreign militants.

The military identified the slain officers as Lt. Col. Karim Baig, Maj. Moeez Maqsood and Capt. Arif Ullah, who were travelling in the area of Kharkamar. Kharkamar is where ethnic tensions with minority Pashtuns hsave flared since last month, when security forces arrested some suspects for their alleged involvement in previous attacks on troops.

Authorities say two lawmakers led a mob attack on a military post at the time to get the suspects released, triggering a shootout that wounded five soldiers and killed several assailants.

The lawmakers face trial for inciting violence.

President Arif Alvi, Prime Minisder Imran Khan and several Cabinet ministers and opposition leaders quickly condemned the latest attack, vowing stern action against those orchestrated bombings.

In the past month, 10 troops have been killed and 35 wounded in separate militant attacks in North Waziristan, where the military years ago declared victory but violence has continued.

Meanwhile, a vehicle carrying three suspected militants fell into the Jehlum canal in eastern Punjab province on Friday, killing all of them, local police officer Tariq Mahmood said.

He said three insurgents in a car sped away when police asked them to halt and their car later fell into the canal when officers were chasing it.

Mahmood said they found explosives and weapons in the car.

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Associated Press writer Asim Tanveer contributed to this story from Multan, Pakistan