TOKYO, Dec. 7 (Xinhua) -- An object possibly from a U.S. military aircraft fell on the roof of a nursery in Ginowan, Japan's Okinawa prefecture, on Thursday, rekindling safety concerns among local residents over the United States bases.
The cylindrical object, about 9.5 cm long and 7.5 cm in diameter, fell on the roof of the nursery when a U.S. military CH-53 transport helicopter was flying in the area, according to public broadcaster NHK.
The object had on it a sign in English that reads "Remove before flight," said media reports.
There were 61 children in the nursery when the incident occurred and 50 of them were playing outside in the grounds, according to the nursery, which was only 300 meters from U.S. Marine Corps Air Station Futenma.
Japanese Defense Minister Itsunori Onodera said in Tokyo that the local defense bureau is checking with the U.S. Marine Corps in Okinawa about the incident.
"We think this kind of incident stirs concerns among the people in Okinawa," he said.
Okinawa Governor Takeshi Onaga said it was a serious accident as people were just one step away from being significantly hurt.
Some 100 people rallied Thursday evening in front of the headquarters of the U.S. military in Okinawa, calling for removal of the bases.
The Futenma air base is located in downtown Ginowan city, Okinawa prefecture, surrounded by residential areas. Local residents have been concerned over flights at the air base causing noise, air pollution and endangering public safety, especially after the crash of a Marine Corps CH-53D transport helicopter on the campus of Okinawa International University in 2004.
The Japanese and U.S. governments have been seeking to move the Futenma base from Ginowan to the less-populated Henoko coastal area of Nago. The people of Okinawa, however, demand the Futenma base to be relocated outside the prefecture.
Okinawa hosts some 75 percent of U.S. bases in Japan while accounting for only 0.6 percent of the country's total land mass.