Tokyo, Dec 13 (IANS): A window of an US military helicopter fell on the grounds of an elementary school in Okinawa in Japan on Wednesday, injuring a student and sparking a backlash from officials.

Authorities said they were notified by the US forces in Okinawa that a window had fallen from a CH-53E transport helicopter. An object was found on the grounds of the Futenma Second Elementary School.

School teachers said around 30 children from the 4th grade were on the school grounds when the metal-framed window struck the ground from the chopper. One child sustained slight injuries, the BBC reported.

The US military apologized. "This is a regrettable incident and we apologize for any anxiety it has caused the community," a statement said.

Okinawa Governor Takeshi Onaga was furious. "It is unforgivable that it dropped in the middle of the playground," he said.

Defence Minister Itsunori Onodera urged the US military to suspend flights of the same type of helicopter until the safety of the chopper can be confirmed.

The incident comes just two months after an American military chopper burst into flames after landing on an empty field in Okinawa.