ROME, Italy?(UPDATE) Two gas-filled railway tank cars exploded in the northern Italian city of Viareggio on Tuesday, killing six people, Lucca province authorities told the Italian news agency ANSA.

The accident injured 50 people, including 20 seriously, officials said.

The explosion came as the train was approaching the station in the coastal city of 50,000 inhabitants northwest of Pisa around midnight, possibly due to a derailment.

Emergency workers said flames engulfed a radius of 300 meters (yards), including five two-story homes located along the railway.

Areas near the station were evacuated in case of further explosions.

The train of 14 railway cars was traveling from the north to nearby Pisa.