Pressure was building on Italian authorities on Wednesday to determine who was to blame for an explosion of a passing freight train that set fire to nearby homes and burned families alive while they slept.

The death toll from Monday night's explosion in the seaside town of Viareggio rose to 16 after a girl aged three and a boy of two died from their burns at hospitals in Rome and Florence. Twenty seven people were injured, many of them seriously.

Italian newspapers demanded to know who was to blame, with La Repubblica asking "Who's Guilty?" and Corriere della Sera warning "No Alibis". Some papers dedicated the first dozen pages or more to the disaster, one of Italy's worst in living memory.

"The Inferno of the Innocent," was the headline of the Rome daily Il Messaggero.

"All of us were afraid. We just didn't understand what was happening, we thought it was a terrorist attack," said Mirko Angelini, a resident of Viareggio, north of Rome.

Infrastructure Minister Altero Matteoli told parliament "checks are underway" into reports the axle on a rail car carrying liquefied petroleum gas appeared to have buckled, causing the derailment and subsequent explosion.

La Repubblica warned in an editorial there were "no small fry" among those possibly responsible.

The train was driven by an employee of Italian state railways, which says it is the country's largest company, while the railcar whose axle may have given way was owned by a subsidiary of U.S.-based GATX Corp.

The conductor of the train, Roberto Fochesato, told Corriere della Sera "we didn't make any mistakes. We found ourselves in an inferno, but it wasn't my fault".

The GATX unit said the railcars were new and issued a statement saying "so far we do not see any connection between the cause of the accident and our wagons".

Rescuers on Wednesday suspended the search for missing victims in the rubble of collapsed homes. One person was still unaccounted for but was presumed to be among the unidentified dead, a rescuer said.

Heart-wrenching stories about the victims dominated the airwaves and newsprint. Corriere told of a mother who rushed out of her home with her five-year-old son Luca, putting him in her car for safety while she ran back inside for her other two children.

The car caught fire while she was gone, and Luca died.

Cable news stations read aloud stories of families killed or in intensive care for severe burns at local hospitals.

"Ilaria and Michela, sisters and friends. The fireball burned them together," was a headline in La Repubblica.

It was Italy's most deadly rail accident since 17 people were killed in January 2005, when a passenger train collided with a freight train near the northern city of Bologna.