Two people were killed as self-defense fighters helped thwart more deadly suicide bombings in Nigeria and Cameroon on Tuesday, officials and witnesses said.

In Maiduguri, northeast Nigeria's biggest city and the birthplace of the Boko Haram insurgency, a lone bomber attempted to attack a mosque near the city's university during morning prayers.

A member of a civilian self-defense force stopped the bomber from reaching the mosque but the bomb killed them both, said police spokesman Victor Isukwu.

The bomber's body was so mangled it was impossible to determine the age or gender, witnesses said. "It took aid workers about an hour to pick up the scattered flesh and bones," said witness Simon Madu.

In northern Cameroon, which also has been regularly targeted by Boko Haram, self-defense fighters alerted soldiers when they saw three bombers crossing from Nigeria toward a village less than 10 kilometers (6 miles) from the border, said Midjiyawa Bakari, governor of Cameroon's Far North region.

The three bombers, two of them women, ran from soldiers and "exploded their devices in a place where cattle ranchers assemble to rest," Bakari said. A 33-year-old resident of the village was killed, he said.

"The casualty figure should have been more but for the timely intervention of the vigilantes who informed the military," Bakari said.

Boko Haram's insurgency has killed more than 20,000 people since 2009.

AP