A Japanese bullet train left one of its doors open while travelling at 280km/h (175mph) on Wednesday.
None of the 340 passengers were injured, and the train’s operator made an emergency stop when he noticed the indicator for the open door.
Passengers on the Hayabusa number 46 bullet train ended up stuck in a tunnel for 15 minutes while checks were made.
The East Japan Railway Company said a cleaner forgot to close the device which manually opens the doors.
Japanese media said the train travelled for about 4km (2.5 miles) with the door open as it slowed to a stop – but no-one was near the open door.
The train arrived in Tokyo some 19 minutes late, Nikkei reported – creating a knock-on effect that caused delays for some 3,000 other passengers.
The national transport ministry asked the company to make sure the issue was not repeated, Japanese media said.
Japan’s famous bullet trains, known as shinkansen, are high-speed rail systems much faster than conventional trains.
The type of train involved in Wednesday’s incident has a top speed of about 320km/h (200 mph), making it one of the fastest on Earth.