Police in southwestern Pakistan say a bomb in a parked car exploded next to a bus heading to a university, killing at least four students and wounding more than 40 other people.

Authorities say the blast occurred Monday in Quetta, the capital of Baluchistan province. Officials tell VOA that a police van providing security for the bus also suffered damage and that police officers are among the wounded.

Police declined to say who they thought was responsible for the attack, but Baluchistan is not immune to such violence. The province bordering Afghanistan and Iran is home to various militant groups, including pro-Taliban factions, as well as, Baluch separatists.

Local residents tell VOA that they believe the government needs to provide more security because the ongoing violence has forced many students to remain at home.

Amnesty International says Baluchistan is one of the most militarized regions of Pakistan, where armed sectarian groups, government security forces and criminal gangs operate with impunity.