A passenger train slammed at high speed into a slow-moving freight train in eastern Belgium, killing three people and sending 10 others to the hospital, authorities said Monday. The accident came just hours after reported lightning strikes and a signal disruption on the line.

Two cars from the passenger train derailed when it rear-ended the freight train around 11 p.m. Sunday in Hermalle-Sous-Huy, a hamlet on the Meuse River. Belgian prosecutor Brigitte Leroy said the passenger train was traveling around 60 mph, and the freight 6-9 mph at the time of the crash. Earlier reports had said the freight train was stopped.

State broadcaster RTBF said the dead included two passengers and the train's driver. RTBF TV reported many of the passengers were students in their early 20s returning to school after the weekend.

Ten people were hospitalized, local hospitals reported. 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. Twenty-seven other passengers were treated at the scene.

Francis Dejon, mayor of St. Georges-sur-Meuse, told a news conference that the passenger train's first car was so badly smashed in the wreck "it was curled back on itself." The second of the six cars also derailed and came to a stop listing on its side.

Belgian railway police and state prosecutors were investigating the cause of the accident.

Belgium's King Philippe and Prime Minister Charles Michel visited the crash site Monday afternoon, thanking rescue workers and viewing the derailed, wrecked rail cars. Michel, through a spokesman, said no effort would be spared to find out why the accident occurred.

It took rescuers three hours to free people from the wreckage of the train, which carried around 40 people when it crashed 17 miles southwest of the city of Liege while traveling from Mouscron to Liers. The wheels and axle of one train car were knocked loose by the impact. A large chunk of wreckage jutted up from the freight train of around 20 cars.

Belgium's national railway operation, SNCB, reported on its Twitter account Sunday 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.

"It's an element we're going to have to look at, but it's premature to see this as the cause of the accident," spokesman Frederic Sacre said.

In June 2008, a similar collision between a passenger train and a freight that was slowing down occurred 100 yards (meters) from the location of Sunday's wreck. A police tribunal in 2010 found the passenger train's driver guilty of causing the accident by ignoring signals. He and the other locomotive driver only narrowly escaped near-certain death, according to Belgian media accounts.

Sacre said it will be up to investigators to determine if there are any similarities with Sunday night's accident.

The wreck halted train service between Namur and Liege, two of Belgium's largest cities, and an SNCB spokeswoman said it could take several days to clear the tracks.

Leroy, the prosecutor, said it may be months before the crash investigation is complete.