Fuel still appeared to be leaking from the wrecked tanker on Saturday morning as police and soldiers tried to clear large crowds of onlookers from the street, according to a Reuters reporter.
The accident scene
A burnt human body and the blackened shells of several cars and motorbikes dotted the road in the eastern Freetown suburb of Wellington, where hundreds had gathered.
The death toll currently stands at 99 with more than 100 casualties being treated in hospitals and clinics across the capital, deputy health minister Amara Jambai told Reuters.
Victims included people who had flocked to collect fuel leaking from the ruptured vehicle, Yvonne Aki-Sawyerr, mayor of the port city, said initially in a post on Facebook that was later edited to remove the reference.
"We've got so many casualties, burnt corpses," said Brima Bureh Sesay, head of the National Disaster Management Agency, in a video from the scene shared online. "It's a terrible, terrible accident."
Videos shared online shortly after the explosion showed people running through clouds of thick smoke as large fires lit up the night sky. Reuters was not able immediately to verify the images.
Accidents with tanker trucks in Sub-Saharan Africa have previously killed scores of people who gathered at the site to collect spilled fuel and were hit by secondary blasts.
In 2019, a tanker explosion in Tanzania killed 85 people, while around 50 people were killed in a similar disaster in Democratic Republic of Congo in 2018.
The mayor said the extent of the damage in Freetown was not yet clear.
"My profound sympathies with families who have lost loved ones and those who have been maimed as a result," President Julius Maada Bio tweeted.
"My Government will do everything to support affected families."