At least three people were killed, 155 others wounded in the blast that occurred at a military depot outside Dar es Salaam on Wednesday, police have confirmed.
Twenty-eight of the wounded are reportedly in critical conditions.
Witnesses said they heard many bomb explosions in the direction of the Tanzania People's Defense Forces base at Mbagala, which is 15 km away from the city center of Dar es Salaam.
Aisha Mahita, chief medical officer at Dar es Salaam's Temeke District Hospital, said the hospital had received two unidentified bodies and over 100 wounded people.
Police Force Operational Commissioner Paul Chagonja said the blast was caused by a fire at the armoury, but "it is too early to establish the cause of the fire."
It was the second such blast at a military armoury in Tanzania.The other one occurred at the Gongola Mboto military base also near Dar es Salaam in 2000 with no human casualties, according to military sources.
In the latest blast, some residents living in nearby areas witnessed military things blown out of the base and landing in the residential area to set ablaze houses.
Local police have decided to conduct a door-to-door search to retrieve lost military materials, especially explosive devices and weapons.
Both police and local residents reported that unexploded ammunitions including rockets and missiles had landed inside residential areas.