4 Youngsters killed in bus-train collision in France
A total of 20 people were taken to hospitals in the nearby city of Perpignan, the prime minister said from Millas.
The accident occurred shortly after 4 pm at a level crossing in the town, located near France's border with Spain.
Two investigations have been launched to determine the causes of the "terrible trauma," Philippe said, asking the media to respect the privacy of the students' families, who went to the school in Millas to await word about the fate of their children.
The families are experiencing "great anguish," he said, because the process of identifying the dead and injured is proving to be slow and arduous.
Mental-health professionals were at the school to offer support to the roughly 300 people gathered there.
The bus was carrying some 25 youngsters between the ages of 8 and 15, while a score of passengers were on the train.
Students on a second bus from the Millas school that was traveling behind the first one saw the horrific crash.
State railway operator SNCF said that the train was traveling at normal speed, roughly 80 km/h (50 mph), and cited witnesses as saying that the crossing gates were in the correct down position at the time of the collision.
The top administrator of Pyrenees-Orientales department, Philippe Vignes, said that only two of the fatalities have been identified so far and seven of the injured have been identified so far.
All of those killed were riding on the bus, while three train passengers suffered minor injuries, Vignes said, adding that the bus driver was among those who were badly hurt.
Televised images showed the bus split into two pieces.
More than 150 police, firefighters and other first responders were working to extract the students from the twisted metal, Vignes said.
First responders set up a field hospital at the accident scene as the critically injured were transported to hospitals by helicopters.
Visibly shaken, Philippe said that the priority was to identify the victims.
President Emmanuel Macron expressed his condolences to the victims' family members on Twitter.