At least 99 people were killed and 92 injured after a fuel tanker exploded in Sierra Leone's capital Freetown, the country's National Disaster Management Agency said.

The tanker exploded in the densely populated suburb of Wellington after colliding with a truck that was carrying granite on Friday.

The collision happened as the tanker driver prepared to enter a petrol station to discharge its fuel, the agency said. As the drivers tried to deal with the resulting fuel leakage they warned residents to stay clear of the scene, it said.

However, locals had approached, collected leaked fuel and stored it in nearby makeshift structures. The fuel had then ignited, the agency said. Motorcyclists, street vendors, bystanders and vehicles were caught in the explosion.

Kpawuru Sandy, secretary-general of the Sierra Leone Red Cross Society, said the number of victims and the nature of their injuries had been difficult for response teams to handle.

"The main hospital is overwhelmed, and families are struggling to identify their loved ones."

Mohammed Mukhier, the organization's regional director for Africa, said more than 100 people were being treated in hospitals in Freetown.

"This is a heartbreaking incident for a country where memories of the 2017 tragic mudslides and the 2014-16 Ebola outbreak are still fresh," he said.

Sierra Leone's President Julius Maada Bio, attending the COP 26 Climate Change conference in Glasgow, Scotland, said he was deeply distressed by the horrendous loss of life.

"My profound sympathies (are) with families who have lost loved ones and those who have been maimed as a result. My government will do everything to support affected families."

Moussa Faki Mahamat, chairman of the African Union Commission, said the organization stands in solidarity with the government and people of Sierra Leone following the accident.

"Our hearts and prayers go to the families of the victims who perished in the horrific fuel tanker explosion in Freetown, and we wish a full recovery to those injured."

Frequent accidents

In recent years there have been several tanker explosion accidents in Africa similar to Friday's, in which victims died trying to collect leaked fuel. In July, 13 people died in western Kenya after an overturned tanker caught fire.

In August 2019, 85 people died after a tanker exploded in the city of Morogoro, Tanzania, and in October 2018, 53 died in the capital of the Democratic Republic of Congo, Kinshasa, in a similar accident. In Kivu, another city in that country, at least 230 people died in a tanker explosion in 2010.