ISLAMABAD - At least three security personnel were killed and three others injured as a powerful bomb went off near their vehicle in Quetta on Sunday afternoon.

The Frontier Corps (FC) personnel were on a routine patrolling and was carrying food for officials when their vehicle was targeted with a bomb planted on the roadside, police said.

The vehicle was adversely damaged in the landmine blast resulting in death of three security personnel and leaving four others were seriously injured.

The dead and the wounded were shifted to the Civil Hospital Quetta. The security forces, bomb disposal squad, and police rushed to the site and cordoned off the area.

A high security alert was announced in the city following the attack, a private news channel reported. The bomb blast came a day after unknown gunmen shot dead a former deputy inspector general of police (DIG) Naeem Khan Kakar near Junior Assistant Colony area of Quetta.

In another attack on Saturday, a rocket-propelled grenade hit a security vehicle in North Waziristan, killing two soldiers and wounding another two.

No one claimed responsibility for any attack.  Violence in Pakistan however dropped significantly since the country's deadliest-ever militant attack, an assault on a school in Peshawar in 2014 that killed more than 150 people, most of them children.

Pakistan military intensified operations against militants in the tribal areas along the border with Afghanistan in the wake of the Peshawar school attack, leading to dramatic security improvements.