South African police have arrested and charged the driver of a gas tanker that exploded near Johannesburg on Christmas Eve.

Police said in a statement that the 32-year-old suspect was charged with multiple counts of culpable homicide, negligent causing of an explosion resulting in death and malicious damage to property.

Over a dozen killed

Authorities said on Sunday the death toll had risen to 15 people following the deadly blast in a residential area in Boksburg, neighboring a hospital.

"In terms of fatalities ... this number has now risen to 15," including three hospital staff members, Health Minister Joe Phaahla said late on Sunday.

"We are told that of those who survived, many of them have quite severe burns, so we still have a long way to go," Phaahla said, in reference to some of the 37 people who were injured.

The gas tanker became wedged beneath a bridge which passes under a railway line on Saturday where it then caught fire.

Scores of onlookers gathered close to the scene as firefighters attempted to extinguish the blaze.

The truck, which was leaking gas, then exploded, engulfing those standing nearby in flames. Footage shared on social media showed the scene shortly afterwards with multiple victims requiring urgent treatment.

Police say a 10-year-old boy also lost his life. The blast caused damage to the nearby Tambo Memorial hospital and resulted in patients having to be diverted to other facilities for treatment.

The driver of the truck will make his first court appearance on Wednesday.