An explosion hit a mosque during evening prayers on Wednesday in Maiduguri, the capital of Nigeria’s Borno state, a Reuters witness said.

Citing sources, AFP news agency reports that at least seven people were killed in the explosion.

Borno state has witnessed frequent terrorist attacks, killing thousands of people and displacing millions across the northeast.

No group has claimed responsibility for the Wednesday attack, but terrorists have previously targeted mosques and crowded places in Maiduguri in suicide bombings and improvised explosive device attacks.

Boko Haram launched its terrorist acts in Borno state in 2009. In recent years, the Nigerian government has made concerted efforts to contain the terrorist group.