Investigators blamed rains for sparking the fires and explosions that killed at least 24 people at a Ministry of Defense-owned fireworks factory in the northern province of Phu Tho Saturday.

Heavy downpours brought by a recent typhoon possibly affected the fiber cement roof of a store at Z121 factory, allowing water to leak through, they said.

The water reacted with aluminum magnesium alloy powder, sparking off fires, they told Deputy Prime Minister Hoang Trung Hai.

Since there was a large quantity of fireworks stored, the fire quickly led to an explosion, which then set fire to adjacent warehouses and workshops and caused more explosions, the inspectors said.

An estimated 17,000 containers of fireworks exploded.

Two hundred and six workers were at the spot when the accident happened, the ministry's General Department of Military Industry reported.

So far 23 have died and 71 others are injured, it said.

Most of the warehouses were destroyed and the losses are estimated at around VND50 billion (US$2.35 million), it added.

The accident also claimed the life of a local resident, who was crushed to death by a tree while attempting to put out a fire in his house, taking the death toll to 24.

Provincial authorities said more than 100 people, including local residents, were admitted to hospital with injuries.