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.
Philippe said that the process of identifying the dead and some of the injured is hard.
The Christian Bourquin school opened today to offer psychological help to children and their families. "Several witnesses confirmed that the barrier had come down so it worked", the spokeswoman said, adding that the investigation would have to clarify what had happened.
SNCF official Gaelle Le Fauche said the train was carrying 25 people, including passengers and crew.
"It was a classic crossing, well equipped and lit".
Four children were killed in the crash.
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. Twelve people were more lightly injured.
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"I go there immediately", tweeted Transport Minister Elisabeth Borne.
An emergency plan has been activated.
"All my thoughts to the victims and their families of this bad school bus accident", French President Emmanuel Macron tweeted.
Forensics experts were combing through debris at the road crossing near the town of Perpignan, close to the border with Spain, as they sought to reconstruct events in the seconds before Thursday afternoon's accident.
Emergency services have been deployed to the site of the accident.
France's Transport Minister Elisabeth Borne, expressing her "very strong emotion following the awful accident", said she was on her way to the site.