At least seven people were killed and dozens injured after the contents from an overturned tanker exploded in a fireball in northern Colombia, police said Monday.

Dozens of people had gathered around the tanker after it overturned and were trying to siphon off fuel when it ignited, causing an inferno, police said. "We believe there are at least seven people burned to death in this tragic accident," said Fabian Ospino, mayor of the town of Pueblo Viejo, where the accident happened, in a video posted on social media.

Local police subsequently confirmed the explosion had killed seven people and left a further 49 people with burn injuries. The accident occurred on the road between the cities of Barranquilla and Santa Marta on Colombia's Caribbean coast.

"There are people who have burns over 90 percent of their body," said Carlos Caicedo, the governor of the local department of Magdalena, who said efforts were underway to transport people suffering serious burns to specialist hospitals.

"We are working with the air force for a medicalized flight in order to be able to send patients to other cities where they have burn wards. Let's not forget that in Magdalena there is no burn ward," said Caicedo.

President Ivan Duque sent a message of solidarity to the families of the victims, saying the situation they faced was "painful."

"The message is one of solidarity with the people who lost their loved ones in this accident," Duque said at an event in Bogota. Hospital services in Barranquilla, around 45 kilometres (28 miles) from the accident, are reported to be close to saturation because of the coronavirus outbreak in one of Colombia's worst-hit regions.