The Tobu Tojo Line resumed operation Thursday after a train carrying some 400 passengers partially derailed the previous day.

The fifth car of the 10-car train derailed at around 12:20 p.m. on Wednesday, forcing passengers to walk to a nearby station. No one was injured.

After the train made an emergency stop between Oyama and Nakaitabashi stations, passengers were ushered along the track to Nakaitabashi Station, about 100 meters away, according to the Metropolitan Police Department.

According to an investigator at the Japan Transport Safety Board, there was a 15-cm crack in a component that connects the train's wheels. It was not immediately clear if the crack occurred before or after the derailment.

Police said they found evidence that the train had scraped against railroad ties for a about 200 meters from a point 50 meters away from Nakaitabashi Station. The transport safety board suspects the train derailed just after it left Nakaitabashi Station.

Police and the safety board are yet to determine the cause of the derailment.

One of the passengers pushed an emergency button in the train after it felt like the car "floated," police said. The train driver subsequently stopped the train.

"It was like a movie. It reminded me of the derailment incident in Amagasaki, Hyogo Prefecture, and it scared me," a male passenger said.

"We deeply apologize for causing trouble," said Yutaka Tsuzuki, a senior executive at train operator Tobu Railway Co., in a news conference Wednesday night.

Tsuzuki said the train, built in 1989, passed a regular checkup on March 7.

The Tobu Tojo Line suspended services between Ikebukuro and Kamiitabashi throughout the day, affecting about 180,000 passengers.