A bomb exploded in Niger’s bordertown of Diffa on Monday hours after Islamic sect Boko Haram attacked a prison there, a military and a local source said.

“A violent explosion was heard in Diffa. I have been informed that it was a car bomb,” said a military source in Diffa, reached by telephone.

A third source, familiar with the situation, said a number of people were injured by the blast, which was followed by shooting in the town. Further details could not immediately be confirmed.