A crash between a bus and a train travelling at high speed in northern Belgium killed four people, including two children, and injured five other children, officials said.
The injured children were taken to the hospital in a serious condition, spokeswoman Lisa De Wilde said at a news conference.
The accident happened on Tuesday at a level crossing during the morning rush hour near the town of Buggenhout, about 30 kilometres (20 miles) north-west of the capital, Brussels.
Ms De Wilde said that the dead included the driver of the minibus and an escort as well as two children.
She said that the cause of the incident had not been established.
Investigators are questioning witnesses and checking for images from cameras mounted nearby.
“What we do know is that the barrier was closed and the red light was on,” she said.
A spokesperson for Belgian rail operator Infrabel said that the train was estimated to be travelling at about 120 kilometres per hour (75 miles per hour) as it approached the crossing and had “no time to brake”.
“The impact was extremely violent,” the spokesman, Frederic Sacre, told RTBF public broadcaster.
Police spokesperson An Berger said that the bus driver appeared to have ploughed through the train barrier.
Infrabel said that the crossing was working correctly.
A security camera there showed that the bus, which had a total of nine people aboard, was still moving when the train hit it.
It is believed that about 100 passengers were aboard the train and that none of them were hurt.
Rail traffic in the area was halted and bus services provided for travellers.
Local officials stood for a minute’s silence after the news conference.
Children played basketball and rode bicycles at a school not far from the scene in the bucolic town.
An Associated Press reporter at the scene said that the badly damaged bus lay toppled on its side.
Forensic experts in protective white suits and wearing gloves were taking photos of the scene and a white pop-up tent was erected nearby.
The train was relatively unscathed.
In a social media post, Belgian interior minister Bernard Quintin expressed “great sadness” over “the tragic accident in Buggenhout, where a school bus was struck by a train”.
“My thoughts go out to the victims and their loved ones,” he said.