A loud explosion has rocked the Kenyan capital, Nairobi, causing a fire and injuring several people.

The blast went off about 1:10 p.m. local time Monday in a central business district near Mt. Kenya University.

Fire and rescue crews rushed to the scene. There was no immediate word on what caused the explosion.

Kenya has been hit with a series of grenade attacks that authorities have blamed on the Somali militant group al-Shabab and its sympathizers. Kenya sent troops into Somalia to fight al-Shabab last October.