"I experienced the apocalypse," said Jeanette Nuongui, the soul 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 added.
At least 100 people, possibly many more, were killed and hundreds more wounded when a weapons depot caught fire, triggering a series of at least five explosions.
Firefighters were finding it hard to fight blazes because of ongoing blasts, officials said, with a military barracks and the area around the munitions depot devastated.
"It was the first explosion that blew everything up," said Victorien-Constant Obani, a soldier whose house was located opposite the barracks. His wife was injured in the arm.
"What happened here was more than a typhoon, more than a civil war," Obani said. "My house was destroyed, I don't know what I am going to do."
The blasts were even felt across the Congo River in the neighbouring city of Kinshasa, capital of the Democratic Republic of Congo, where windows shattered on some buildings.
Soldiers said a blaze in two munition depots in the Mpila armoured brigade barracks, in east Brazzaville, had triggered the explosions.
"I was terrified by the smoke climbing into the sky," said Willy Kaba, who arrived soon after the first explosion at about 0800 GMT. "After plucking up courage, I approached the scene and saw the whole munition camp destroyed -- the buildings, the walls."
Resident Dutroc Messengo said a young man had lost both legs and another was killed when their house collapsed.
Another resident, Blaise Mongo, said women and children had fled to neighbourhoods away from the ruined area, while men stayed behind to protect what little remained from looters.
Near the barracks, three churches were damaged or destroyed and houses could be seen with their roofs hanging off, their doors broken and windows blown out.
Xinhua news agency said some 140 Chinese workers from the Beijing Construction Engineering Group were working near the munitions depot when the blasts occurred.
The dormitory building of China's Huawei company was badly damaged, but there were no casualties reported there, Chinese officials said.
