KABUL, Afghanistan >> Three suicide bombers killed at least 20 people on Tuesday in a normally peaceful city in southwestern Afghanistan, an official said.

The triple bombing in Nimroz province was the latest in a month of violence in which Taliban insurgents and their allies have ratcheted up attacks as international troops increasingly hand over responsibility for security in the country to Afghan police and soldiers.

Nearly 50 people were wounded in Tuesday’s explosions in the provincial capital of Zaranj. The bombings came a day after local authorities rounded up several other suspected insurgents preparing for suicide attacks in the area, Nimroz governor Abdul Karim Barawi said.

In the first explosion Tuesday, one bomber detonated his explosives belt in the heart of the city. Almost at the same time, police opened fire at two other attackers in other parts of the city, accidentally setting off their explosives, Barawi said.

Most of those killed were civilians rushing to buy food to break the daily fast for the holy month of Ramadan, he said.

Nimroz is one of Afghanistan’s relatively peaceful provinces but has seen an increase in violence recently. On Saturday, an Afghan police officer killed 11 of his fellow officers in the remote Dilaram district of the province.