ABUJA, Nigeria (AP) — At least 33 people have been killed after Islamic militants launched simultaneous attacks on a district in northwest Nigeria, according to the police.

The attack took place on Wednesday in the Biu community of Kebbi state, police spokesman Bashir Usman said in a statement late Thursday night.

The assailants crossed from Sokoto state, parts of which are occupied by the Lakurawa insurgent group, Usman said.

“Preliminary investigations confirm that armed Lakurawa militants entered the area to rustle cattle,” he said, adding that security personnel have been deployed to restore calm and maintain order.

The Lakurawa group operates in parts of northwestern Nigeria, particularly around communities in the northwestern state of Sokoto. The armed group is known to engage in cattle rustling, raids on villages and kidnappings for ransom.

Northern Nigeria is in the grip of a complex security crisis featuring both Islamic militants and armed criminal gangs kidnapping people for ransom.

The West African nation is in security cooperation with the U.S. after initial diplomatic tensions. Earlier this week, the Nigerian military announced the arrival of 100 U.S troops in Nigeria to help train its military in its fight against armed groups.