An Afghan official says three suicide bombers have killed at least 20 people in a city in the country's southwest.

The triple bombing in Nimroz province also wounded at least 48 people. Governor Abdul Karim Barawi says the bombers struck in the provincial capital of Zaranj on Tuesday afternoon. He says one suicide attacker detonated his explosives belt in the heart of the city. Police then opened fire at the other two bombers, accidentally setting off their explosives.

The governor says the attacks came a day after local authorities rounded up several suspects in the area.

Nimroz is a relatively peaceful province but it has seen an increase in violence recently. On Saturday, an Afghan policeman killed 11 of his fellow officers in the province's remote Dilaram district.