(CNN) -- The death toll climbed to 15 on Wednesday in western Italy after a cargo train loaded with liquefied petroleum caused an explosion, civil protection agency officials said, warning more victims could be found.
Firefighters check a wrecked freight train in Italy after gas tankers exploded.
Crews searched for people who remained unaccounted for in the disaster, which happened late Monday.
The 14-car cargo train -- loaded with liquefied petroleum -- was traveling through the seaside town of Viareggio when it sprang a leak and derailed. Fuel spilled onto streets, causing an explosion and starting a fire in a nearby neighborhood. Many residents were asleep at the time.
About 30 burn victims were still in hospitals Wednesday, civil protection officials said. About 12 of them were in critical condition. Two children were among the severely burned, Guido Bertolaso, head of the civil protection, had said earlier.
"I heard the explosion and I went out into the street to find myself faced with flames and a motionless, charred body lying on the ground," a witness told the Italian news agency ANSA.
"It was a terrifying scene which I will never forget," the witness added. "We couldn't do anything for the body except cover it up." iReport.com: Flames turn sky orange after train explosion
Another witness said a girl riding by on a scooter was caught in the blast and threw herself on the ground to put out her burning clothes.
The train, which was hauling tanker cars through a station, was traveling from La Spezia to Pisa, said Antonio Garufi, a local government official.
Minister of Transportation Altero Matteoli opened an investigation into the accident. He wants to see whether safety rules were breached, or whether regulations fall short. He is to present the findings to the Italian parliament.
Mauro Moretti, chairman of Italian Railways, told local television Tuesday that one of the wagon locks may have malfunctioned. He said the train conductor didn't appear at fault. He was driving at an average speed of 90 km per hour, Moretti said.
Authorities have called the accident one of Italy's worst rail tragedies.
CNN's Hada Messia in Rome contributed to this report.
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