“The investigating team is exploring the possibility that the blast was caused by criminals using an improvised explosive device,” Kiraithe said in a statement.

There are still confusions over the exact cause of the blast in shopping complex in Kenyan capital, Nairobi, on a busy Monday afternoon.

Moments after the blast, Kenya police commissioner suggested that an electric fault might have caused the massive explosion, however, a spokesperson for Kenya Power, the country’s electricity distributor said that earlier investigations had ruled out any electrical malfunction.

Kenya has seen a series of explosions and grenade attacks in recent months with Kenya leaders often blaming al-Shabaab fighters and their sympathizers for the attacks.

Kenya sent its troops to pursue al-Shabaab fighters in Somalia last year.