Lagos, Nigeria (CNN) -- A pair of explosive attacks in northeast Nigeria killed 11 people, a spokesman for Borno state police said Wednesday.
The attacks took place Tuesday at a police station and outside a church, said Abdullahi Lawal, the police spokesman.
In the first incident, "unknown gunmen suspected to be Boko Haram attacked Gwange police station," Lawal said. "They threw local explosives into the police station premises."
Boko Haram is a militant Islamist group that has challenged Nigeria's government. It is regarded as a fringe group in northern Nigeria and is opposed by the Muslim establishment in the country.
Lawal said the attack at the police station lasted about 1 1/2 hours, and military backup was called to assist.
Police "returned fire and contained the incident," which eventually led to the deaths of nine people -- including seven suspected attackers and two passers-by, Lawal said. One other person was wounded.
Another explosion took place outside St. Patrick Catholic Church in Borno state Tuesday, Lawal said. Two people were killed and three were wounded in that attack, he said.
Boko Haram is also suspected of killing Islamic cleric Ibrahim Birkuti on Monday. Birkuti was gunned down by men on a motorbike.