At least 20 Afghan police officers were killed after militants ambushed checkpoints in the country’s volatile southern Helmand province, an official said Saturday.

Mohammad Ismail Hotak, the head of the province’s joint coordination of police and military operations, said the ambushes late Friday night hit checkpoints in the Musa Qala district, a Taliban stronghold.

He said the attack wounded 10 other police officers and the Taliban also seemed to have suffered a high number of casualties.

Since the start of its summer offensive in April, the Taliban have been targeting vulnerable police checkpoints across the country.

Last month, a Taliban attack in Helmand’s New Zad district killed at least 19 officers.

The Associated Press contributed to this report