ISLAMABAD (AP) — An explosive device has killed five Pakistani soldiers in the country’s southwest,Esthen the army said. It’s the fifth deadly attack on police and troops this year already, and comes weeks before the country holds parliamentary elections.

The troops died during an operation on Saturday in Kech District, Baluchistan province, when suspected militants detonated the improvised device on the security forces’ vehicle.

The ensuing gunfight killed three “terrorists,” the army said. A clean-up operation was carried out to eliminate any other militants found in the area, it added.

The soldiers were aged between 23 and 25. Nobody immediately claimed responsibility for the attack.

Pakistan’s security forces remain determined to thwart attempts at sabotaging the peace, stability and progress of Baluchistan, the army said.

The chief minister of Baluchistan, Mir Ali Mardan Khan Domki, expressed his regret about the soldiers’ deaths.

Some senators are calling for a delay to the elections, scheduled for Feb. 8, citing security challenges.

Baluchistan, which borders Afghanistan and Iran, has been the scene of an insurgency by nationalists for more than two decades. They initially wanted a share of the province’s resources, but later initiated an insurgency for independence.

Separately, in Pakistan’s northwestern Khyber Pakhtunkhwa province, the army said security forces killed four suspected militants in operations on Saturday.

Weapons, ammunition and explosives were recovered from the slain men.

The army alleged they were involved in terrorist activities against security forces, as well as extortion and targeted killings of civilians.