Four railway workers have died after being struck by an express train while carrying out weeding work on the tracks at a station in Japan’s Tochigi prefecture.

The four men, who were in their 50s and 60s, were hit at about 10.45am local time on Thursday at Shin-Kanuma station in Kanuma, north of Tokyo, according to police and Tobu Railway, which operates the line.

The workers were part of a seven-person team clearing weeds from the railway tracks when they were struck by a six-car Spacia X limited express train travelling towards Tokyo’s Asakusa Station from Tobu-Nikko Station.

Three of the victims were found on the tracks following the collision, while the fourth was found on the station’s platform.

All four were taken to hospital, where they were later confirmed dead.

The train was approaching Shin-Kanuma and was due to stop at the station when the accident happened.

About 50 passengers were aboard the train, but none were injured, Tobu Railway said.

The other three workers involved in the maintenance operation escaped injury.

The collision brought services on part of the Tobu Nikko Line to a temporary halt. Trains between Shin-Tochigi and Shimo-Imaichi stations were suspended before services resumed at 3.22pm local time.

The circumstances of the crash are now being investigated, particularly how the workers came to be on the tracks when the train approached.

Tobu Railway said a safety system designed to protect workers from approaching trains was in operation at the time.

Under the procedure, a designated lookout monitors the tracks for approaching trains and warns workers to move clear.

“The usual lookout system was operating as normal - when a train approaches, a lookout waves a flag and, once the driver acknowledges it, sounds the horn,” a representative from Tobu Railway told the BBC.

“We are currently investigating why the accident occurred despite this.”

A passenger on the train told Japanese broadcaster NHK that they heard a “strange noise” before the train made an emergency stop.

Passengers were then kept aboard for a period while railway staff investigated what had happened.

Fatal railway accidents are relatively uncommon in Japan, which has one of the world’s most extensive passenger rail networks.

The train involved in Thursday’s crash was a limited express service, a category of high-speed trains that is second only to the Shinkansen bullet trains in speed.