A train derailed near The Hague in the early hours of Tuesday, sending two carriages into a field next to the tracks, Dutch emergency services said. One person died and some 30 passengers were injured, many of them seriously.

Television images showed people using makeshift bridges to cross a canal running alongside the rails to reach the stricken train in the darkness. Many windows in the train carriages were broken. It was not clear if that happened during the accident or as passengers attempted to escape.

Photos from the scene showed two of the bright yellow and blue train carriages perpendicular to the tracks lying across a small canal and partially in a field. What appeared to be the front of the train was badly damaged. Other parts of the train were partially derailed.

Images showed a freight train also stopped on rails close to the wreckage of the passenger train.

Injured passengers were treated in homes near the line and transported in a fleet of ambulances to hospitals, including a “calamity hospital” opened in the central city of Utrecht.

The cause of the accident that happened around 3:25 a.m. (0125 GMT) in the town of Voorschoten, near The Hague, was not immediately clear. Dutch media reported that there was a small construction crane on the tracks, but authorities did not immediately confirm that.

The local fire brigade tweeted after the crash that it appeared to be a collision between a passenger train and “building material.”

“A terrible train accident near Voorschoten, where unfortunately one person died and many people were injured. My thoughts are with the relatives and with all the victims. I wish them all the best,” Dutch Prime Minister Mark Rutte said in a tweet.

Dutch King Willem-Alexander and Queen Maxima also expressed their sympathy in a tweet.

Ingrid de Roos, a spokeswoman for local fire services, told news show WNL that a small fire broke out at the rear of the train but was quickly extinguished.

John Voppen, CEO of the rail network company Pro Rail, called the accident “a black day for Dutch railways” and said the cause was under investigation.