A police officer accidentally fired a pistol inside a vehicle parked near the venue of the World Exposition in Osaka, police said Monday, adding that no one was injured.

The 28-year-old male riot squad member mistakenly pulled the trigger when putting the pistol back in its case at around 7 p.m. Sunday, after finishing a security shift at the international event in the western Japan city, according to the Osaka police.

The handgun was fired downward, with the single discharged bullet making a hole in a seat and leaving a mark where it appears to have been embedded in the floor of the vehicle, they said.

Four other male officers were in the vehicle parked in an area off-limits to the public. The police vowed to prevent a recurrence and said the incident has not disrupted expo security operations.

The six-month world expo on Yumeshima, a man-made island in Osaka Bay, runs through Oct. 13.

Related coverage:

World Expo water shows halted after detection of legionella bacteria

AloJapan.com