Dec. 13 (UPI) -- For the second time in less than a week, U.S. officials said a part from a military helicopter fell off while in flight over Japan and landed on a school.
The U.S. Marine Corps said a window from a CH-53E helicopter detached and fell into a field near an elementary school in Okinawa. The chopper was based at Marine Corps Air Station Futenma.
The Marine Corps said in a statement the incident happened just after 10 a.m. Tuesday at Daini Futenma Elementary School.
The helicopter's window landed about 30 feet from where dozens of children were playing, Japan's NHK television network reported -- and shattered when it hit the ground. One child received a slight hand injury.
"We take this report extremely seriously and are investigating the cause of this incident in close coordination with local authorities. Updates will be provided as information is made available," U.S. Forces, Japan said in a statement. "This is a regrettable incident and we apologize for any anxiety it has caused the community."
The school's principal said the children were "so upset that the school cannot resume physical education classes anytime soon."
Authorities say the window, which fell from the left side of the cockpit, weighs about 15 pounds.
The commanding general of Marine Corps installations in the Pacific said all CH-53E choppers at the Futenma base have been grounded for safety checks.
Tuesday's incident came less than a week after a part from another Marine Corps CH-53 helicopter fell onto the roof of another school in Okinawa. No one was hurt.
Police said that part was made of plastic and had a label that said, "remove before flight."