The death toll from an explosion of a tanker truck on Christmas Eve near eastern Johannesburg has risen to 34, including 10 health workers at a nearby hospital.

The truck was carrying gas when it got stuck under a low-lying bridge in the town of Boksburg, sparking flames. As firefighters tried to extinguish them the tanker exploded, according to emergency services officials.

A “fire bomb” from the explosion substantially damaged Tambo Memorial Hospital, located about 100 metres away, authorities said. Several health workers were in the hospital’s parking lot, some about to leave after their shifts and others trying to move their cars away from the fire.

In addition to the loss of life, the hospital’s emergency unit and X-ray department were badly damaged, Minister of Health Joe Phaahla said.

Other fatalities were residents who had gathered to see the burning truck. At least 321 injured people were taken to the damaged hospital, though some were later transferred to others in the Johannesburg area.

Several houses and vehicles were also damaged by the explosion, according to officials.

“A fireball in the sky,” resident Rolf Bjornstad told South Africa’s News24 website.

“There was heat coming into the house. I thought of my wife, kids, and helping the affected people,” he said.

The South Africa Council of Churches held a memorial service for all those killed in the accident.

The 32-year-old driver was taken into custody a few days after the accident but then was released by officials who said there was insufficient evidence to charge him.

The tanker truck transporting liquefied petroleum gas — used in homes and industries for heating and cooking — was en route to Botswana from South Africa’s Indian Ocean port of Richards Bay, said officials.