COPENHAGEN, Denmark — A passenger train collided with an armored vehicle in southern Sweden Tuesday, injuring the train driver and three Swedish military staff, authorities said.

The accident happened near Trosa, south of Stockholm, police said.

“We heard a bang, it sounded loud and it felt liked the train had derailed,” passenger Atia Rasul told the Expressen daily.

Police said the driver suffered a light injury.

The armored vehicle was taking part in Aurora 17, Sweden’s largest military exercise in more than 20 years with nearly 20,000 troops drilling on air, land and sea. The drill involves troops from Sweden, Finland and NATO soldiers from Denmark, Norway, France, Estonia and Lithuania.

The Swedish military said the vehicle involved in the crash was an Armored Modular Vehicle, and three troops with a regiment based in southern Sweden were injured. It was unclear how serious their injuries were but all three were taken to a hospital.

Built in Finland, the eight-wheeled vehicle is used by the Swedish, Finnish and Polish armies, among others.

Rescue officials said there was a total of 70 passengers on the train but none suffered injuries.