MILLAS: The death toll from a crash between a school bus and a train in southern France rose to six Friday as two 11-year-old girls succumbed to their injuries, a police source said.

Four teenagers had died on Thursday in the accident at a level crossing in Millas, a village near the city of Perpignan. Eighteen others were injured, 14 of them children.

Authorities are investigating whether human error or a technical fault was to blame for one of the worst accidents involving a school bus in France for 30 years.

The impact ripped the bus in half and forced the train off the tracks.

Investigators only finished identifying the dead overnight due to the severity of their injuries, with the mayor of the neighbouring village describing the scene as "a vision of horror".

The female driver of the bus was among the injured and has not yet been questioned, but Perpignan prosecutor Jean-Jacques Fagni said investigators had spoken to the train driver.

It is unclear whether the automatic barriers at the crossing were open at the time of the crash, though national rail operator SNCF said that "according to witnesses, the level crossing was functioning normally".