The fires that raged on for two days after a deadly explosion in a munitions' depot in the Republic of Congo have been brought under control, authorities say.

The explosions on Sunday were so violent they flattened buildings, killing at least 246 people and trapping countless others under the falling debris.

Small explosions continued to shake Brazzaville on Monday, though the blasts were not nearly as loud as those that had convulsed the city the day before, causing windows to shatter in a 5km radius of the depot.

"The two fires have been brought under control since yesterday," Colonel Jean-Robert Obargui, a defence ministry spokesman, told the AFP news agency on Tuesday.

Obargui said that even if the fires were under control, "for the moment, we can't" say that a second munitions depot, about 100 metres from the one that exploded on Sunday, was no longer in danger.

Russian, French and Congolese experts were dispatched to the area to avoid the fires, which the government said were caused by an electrical short-circuit, from reaching the second depot of even heavier weapons.

Raymond Mboulou, the country's interior minister, speaking to AFP on Monday, described the scenes of devastation in the streets surrounding the military barracks "like a tsunami without water".

Thousands of people filled Mpila's streets for news of relatives, as authorities opened two churches and a covered market to house those left homeless by the disaster.

"I experienced the apocalypse," said Jeanette Nuongui, the sole survivor from a family home that was destroyed in one of the blasts that rocked Brazzaville.

"It is by the grace of God I am here. My mother died, my father, my two brothers and my two sisters also. There's nothing left," she said.

The explosions, which began around 8am local time on Sunday, were heard across the Congo River in Kinshasa, the capital of the neighbouring Democratic Republic of Congo (DRC).

The explosions triggered panic in Kinshasa, but DRC state television urged residents to remain calm.