Officials from the East Japan Railway Co. (JR East) said the accident happened at around 1:10 AM on the Keihin Tohoku Line close to the Kawasaki Station. The train, on its last trip for the night, was going on a speed of about 60 kph when it hit the maintenance car. The driver, seeing the car around 100 to 200 meters away, stepped on the brakes to stop from moving forward, but was unable to do so in time. Both the driver and conductor were trapped inside as the first two carriages of the 10-car train derailed upon impact. The 43-year old driver of the maintenance car on the other hand was unharmed as he jumped off the vehicle before the train hit it. Firefighters who responded to the scene smashed windows and were able to retrieve the injured men.
Other trains running on the Keihin Tohoku Line between the Kamata and Tsurumi stations were temporarily suspended as the company investigated the accident. Initial investigations by JR East showed that the maintenance car went onto the tracks for the night-time renovations without confirmation if it was safe to enter, causing the crash.