Dec. 7 (UPI) -- The U.S. Marine Corps is investigating whether part of an U.S. military helicopter fell onto the roof of a nursery school in Okinawa, Japan, on Thursday morning.
The small cylinder fell on the roof of Midorigaoka Nursery School after a CH-53 passed over the school after 10 a.m., Japan television network NHK reported.
The Christian school, which is in a densely populated residential area, is about 2.5 miles from Marine Corps Air Station Futenma.
None of the 61 children and 10 staff members at the school during the time were injured, including some children playing outside, NHK reported.
Local police said the object is about 4 inches long and 3 inches wide, clear and made of plastic with a label that says in English to "remove before flight," Kyodo News reported.
"We take this report very seriously and are investigating this incident working closely with local authorities," the Marine Corps said in a statement to ABC News. "We care deeply about the safety of our friends and neighbors in the communities around which we live and operate. We will provide more information as it becomes available."
Okinawa Gov. Takeshi Onaga told Kyodo News that "one wrong move and somebody could have got injured or died. We think this is a serious accident."
Most of the U.S. military operation in Japan is located at Futenma.
The Japanese and U.S. governments plan to relocate the Futenma base from Ginowan to the less populated Henoko coastal district of Nago, also in Okinawa Prefecture.
But Onaga wants the Futenma base to be removed from the prefecture altogether.
Last December, Japan's top court ruled in favor of the central government's plan to relocate a U.S. Marine base within Okinawa. The Supreme Court said Okinawa Gov. Takeshi Onaga acted "illegally" when he revoked an October 2015 order by his predecessor, Hirokazu Nakaima, for the landfill work of the relocation plan.
In October, a CH-53 helicopter made an emergency landing near the U.S. military's Northern Training Area in Okinawa. Even though the helicopter burst into flames, none of the seven crew members or local residents were hurt.
On Thursday, the Tokyo metropolitan government said a U.S. military C-130 transport aircraft assigned to the Yokota Air Base in western Tokyo lost some equipment to release flares.