April 17 (UPI) — One of Japan’s famously punctual high-speed bullet trains experienced a rare 17-minute delay when a snake was found in a passenger car.

The Central Japan Railway Company said the train arrived in Tokyo from Nagoya and its departure to Osaka was called off when a passenger alerted station staff to the presence of a 16-inch snake slithering through a passenger car.

The train, a shinkansen bullet train, was taken out of service, causing a 17-minute delay for more than 600 passengers while another train was assigned to the route.

The snake was captured, but the exact type of serpent found aboard the vehicle has not yet been revealed. Officials said they are investigating how the slithering stowaway ended up on the train.

“It’s difficult to imagine wild snakes somehow climbing onto the train at one of the stations. We have rules against bringing snakes into the shinkansen,” a Central Japan Railway spokesman told The Japan Times. “But we don’t check passengers’ baggage.”