LAGOS, Nigeria (AP) — Nigerian police say gunmen have kidnapped four British nationals in the Niger Delta region.

Police spokesman Andrew Aniamaka said Wednesday the four were abducted around 2 a.m. in Enukorowa community in the Burutu local government area. He says they include a doctor, his wife and two other men who were involved in preaching and providing free medical services to residents.

Aniamaka says it is believed that militants carried out the kidnapping. No ransom demand has been made.

Kidnapping for ransom is common in Nigeria. An Italian priest was kidnapped Oct. 12, though Italy's foreign minister said Wednesday he has since been freed.