ISLAMABAD - At least 19 Shiite Muslims were killed when a bomb destroyed two buses in southwestern Pakistan on Sunday, a senior administration official said.

The blast occurred in Mastung district of Balochistan province, which has seen numerous attacks on the minority Muslim sect.

“Nineteen bodies have been retrieved from the wreckage of buses,” said Tufail Baloch, deputy commissioner of Mastung. “Up to 25 people, including four women, have been injured.”

Baloch said the buses were traveling under escort, adding that at least two security officers also sustained injuries in the explosion.

Dunya news television quoted security sources as saying that a suicide bomber detonated his explosives-laden car next to the convoy, but there was no immediate official confirmation.

In Balochistan, Shiites have been a frequent target of attacks, mostly blamed on radical Sunni groups that also have links with Islamist insurgents.