Four children have been killed when a train smashed into an electric cargo bicycle in the eastern Dutch city of Oss. A woman and another child were seriously injured.

Police said the accident happened at a rail crossing close to the town’s railway station, which has warning lights and red and white barriers to keep pedestrians off the tracks when trains pass.

They said the electric bike belonged to a children’s day care centre and was taking children to school when the crash happened.

There were multiple witnesses, including other school-age children, police added.

Cargo bikes, which have a large wooden box mounted on the frame in front of the rider, were formerly used for transporting goods but are now popular among Dutch parents for carrying young children.

“We have informed the families involved of this terrible news,” police said in a statement. “We are investigating how this could have happened.”

Rescue personnel work at the scene of the accident in the city of Oss, Netherlands (REUTERS/Piroschka van de Wouw) (Reuters)

Two air ambulances landed at the scene of the accident and the two critically injured victims were taken to a local hospital.

The Dutch Safety Board are investigating the cause of the accident.

The mayor of Oss, Wobine Buijs-Glaudemans, said local authorities “stand with the families, the school, the day care centre and everybody else involved.”

Two critically injured victims were taken to a local hospital (AP/Charles Mallo)

ProRail, the company responsible for rail infrastructure in the Netherlands, said in a statement that the cause of the collision is under investigation.

“This is a very dark day, terrible for the next of kin and those involved,” said ProRail CEO Pier Eringa. “There are no words to describe this.”