The fuel tanker blast caused apocalyptic scenes, with passengers on a bus crossing the Bridge of the Americas coming close to being engulfed by the fireball and clouds of smoke.

Passengers could be seen getting up from their seats and moving quickly away from the windows as the flames and black smoke appeared to close in on them just after 4pm yesterday.

The man killed is believed to be an employee at a complex where tanker trucks are supplied with fuel.

Firefighters took three hours to put out the blaze and make the area safe.

A spokesman for Panama's Fire Brigade Service confirmed: 'Unfortunately, a person has died, possibly a collaborator of the company, who was trapped at the time when the fire and subsequent explosion of tanker vehicles occurred.

He said two of the people injured were civilians and the other two firefighters who were 'out of danger.'

More than 70 firefighters and 45 emergency response vehicles were sent to the scene in an initial mobilisation.

According to Bomberos Panama, the inferno, caused by the explosion of multiple tanker trucks, 'spread quickly following the initial detonation, generating multiple explosions and a dense column of smoke that covered the area, while vehicles traveling down the road were left in the middle of the emergency.'

The Ministry of Public Works announced the temporary closure of the bridge following the fire.

'This preventive measure is taken with the aim of ensuring the safety of the drivers, while the specialised technical teams carry out the relevant pathological technical inspection to verify the structural conditions of the bridge,' the ministry said. 

'The crossing will remain closed until it is confirmed that traffic is completely safe and technical results are provided to support it.'

The Bridge of the Americas, completed in 1962 at a cost of £15.2million, was closed after the incident so officials could check for structural damage.

Unconfirmed local reports said the explosion occurred when workers were transferring fuel to a tank.