KANO, Nigeria — Militants struck the central mosque in one of Nigeria’s biggest cities on Friday, intensifying the violence that has swept across the nation’s north in recent months.

Explosions shook the mosque, in the northern city of Kano, during Friday Prayer, scattering worshipers and sending an enormous plume of black smoke into the air.

A state deputy police commissioner, Sunusi Lemu, said 35 people had been killed and 150 wounded. But some estimates were far higher, as corpses quickly piled up in hospitals and some still lay on the ground.