Updated - No one died but as many as 56 people are in hospital after a gas explosion ripped through Khai Son Industrial Zone in Bac Ninh northern province on Wednesday.

Eyewitness told Tuoi Tre that at first they heard many explosions at An Duong gas company and later saw a huge burst of fire soaring into the sky, sending hundreds of workers at the zone into panic.

Many 13-kg gas cylinders were found in disorder at the scene, with some lying hundreds of meters apart.

Nguyen Dang San, deputy head of the zone’s management board, told VNA that the blast occurred at around 9:30am when employees from a gas company were pumping gas into a tank.

As the result of the explosion, a gas truck was burnt down and the ceiling of a warehouse of the adjacent company collapsed.

Among the injured, two reportedly suffered severe burns and are being treated at Hanoi-based Vietnam National Institute of Burns.

After being informed of the incident, Bac Ninh police immediately deployed four fire trucks to the scene.

The explosion has caused an estimated loss of VND2 billion (US$96,000), the zone’s officials said.

Local police are carrying out further investigations to identify the main cause of the accident.

Here are some photos of the blast scene:

The blast scene. Photo by Tuoi Tre

A gas tank blown up in the blast. Photo by Tuoi Tre

The blast scene. Photo by Tuoi Tre

Many 13-kg gas cylinders were found in disorder at the scene, with some lying hundreds of meters apart. Photo by Tuoi Tre

Broken window glasses seen after the blast. Photo by Tuoi Tre