Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

A high-speed passenger train slammed into a slow-moving freight train at around 11 p.m. Sunday in Hermalle-Sous-Huy, eastern Belgium, killing three people and sending 10 others to the hospital, authorities said Monday. Twenty-seven other passengers were treated at the scene.

The wreckage of a passenger train is pictured after it crashed into the back of a freight train in the eastern Belgian municipality of Saint-Georges-Sur-Meuse, June 6, 2016. REUTERS/Francois Lenoir FRANCOIS LENOIR / Reuters

Belgian prosecutor Brigitte Leroy said the passenger train was traveling around 60 mph (100 kph), and the freight 6-9 mph (10-15 kph) at the time of the crash.

Rail workers walk next to the wreckage of the passenger and freight train after they collided, on June 6, 2016. Virginia Mayo / AP

Belgium's national railway operation, SNCB, reported that there was "a signals disruption" on the rail line about an hour and a half before the wreck occurred, but said the problem had been solved. A spokesman for Infrabel, a separate company that oversees Belgium's rail infrastructure, said installations where the wreck occurred "were hit by lightning" earlier Sunday.

But the cause of the accident has not been decided yet.

Shattered window after the collision. Virginia Mayo / AP

As of midday Monday, Belgian media said only one of the injured was still being treated: a 26-year-old man who underwent two operations for broken ribs and vertebrae and abdominal pains.