SANTIAGO, Feb. 21 (Xinhua) -- The death toll from a truck explosion on a highway in Chile's capital Santiago has risen to six, Chilean health authorities said on Saturday.

The two latest victims died in hospital from severe burns despite medical efforts, the authorities said, adding that 15 people remain hospitalized with serious injuries, 14 of whom are in critical condition.

The explosion occurred on Thursday due to a suspected gas leak from the truck. The fire triggered by the explosion spread to other vehicles on the highway and in a nearby parking lot. The blast caused a large fireball and smoke visible from various parts of the capital.

Further investigation is underway.