The blasts sent thousands of residents into a panic and forced authorities to shut the country's main airport [Reuters]

A series of blasts at a military ammunition depot has killed at least 20 people in Dar es Salaam, Tanzania's commercial capital, Mizengo Pinda, the country's prime minister said.

On Wednesday night, a chain of explosions lit up the night sky and sent thousands of Dar es Salaam residents into a panic, and forced authorities to shut the country's main airport.

The blasts hit the Gongo la Mboto military base in Ilala district, a few kilometres from the Dar es Salaam International Airport.

"The explosions occurred at the main military arms depot in Dar es Salaam. The airport was closed last night as a precaution," Hussein Mwinyi, Tanzania's defence minister, told Reuters news agency.

The blasts scattered debris across densely populated neighbourhoods several kilometres away from the military base.

"I live some 15 kilometres from the military base, but my neighbour's house was struck by debris from a rocket propelled grenade. Luckily, no one was injured because we were told to evacuate our homes," Hassan Kondo, a resident of the Kivule area on the outskirts of Dar es Salaam, said.

"The situation is calm now. There was no major damage to the airport's infrastructure," Mwajuma Kiponza, commander of the Dar es Salaam airport police unit, told Reuters.

Kiponza said that as of Thursday morning, the airport remained closed to air traffic.

Toll may rise

Meanwhile, Pinda told parliament on Thursday that 4,000 people had sought shelter at the national stadium.

Some 23 ammunition depots, a secondary school and two houses were also razed.

"The death toll might rise when we ascertain the full extent of the damage caused by the explosions," Pinda said in a statement to parliament.

The prime minister said he had convened an emergency security meeting over the blasts and added that the country's armed forces were investigating the incident.

There was no indication of foul play and such incidents have happened before in Tanzania.

In April 2009, 26 people were killed and more than 700 wounded by a string of powerful blasts at an arms depot in Dar es Salaam, which officials said were accidental.