A window fell from a U.S. helicopter onto a school sports field near a U.S. Marines air base on Okinawa on Wednesday, the Marines said, the latest in a series of accidents that have fanned safety concerns on Japan’s southern island, Reuters reports.

Japan’s central government and Okinawa authorities have been at odds for years over the Futenma base. Residents complain about what they see as the unfair burden they carry in supporting the U.S. military presence in Japan.

A 10-year-old boy suffered a minor injury but the exact cause was unclear, an Okinawa prefecture official told Reuters. The boy was among about 50 children on the elementary school grounds when the window fell from a U.S. CH-53E transport helicopter.

Japan’s Chief Cabinet Secretary Yoshihide Suga said: "This sort of incident creates anxiety not only among those involved with the school but the people of Okinawa and should never happen.”

Suga told a regular news conference that the government would respond appropriately after getting an explanation from U.S. officials.

Icmal.Az