A Japan Coast Guard patrol vessel has accidentally fired at least eight bullets from an autocannon toward the ground on an island in Okinawa Prefecture. No casualties or damage have been reported.

Coast Guard officials said the incident happened on Tuesday morning during an inspection of the 20-millimeter-caliber autocannon mounted near the bow of the patrol vessel Shimoji. The ship was anchored at Port Nagayama on Irabu Island in the prefecture.

The cannon was pointed at bushes extending about 80 meters long, in front of a prefectural road and farming fields.

Coast Guard officials have been looking for the fired bullets and questioning the personnel who were inspecting the gun.

Fukumoto Takuya, head of the Miyakojima Coast Guard Office, which oversees the area, apologized to local residents in a statement. He said his office will do its best to find out what caused the problem.

Six years ago, the Shimoji was deployed at the Miyakojima Coast Guard Office to tighten controls on illegal fishing by foreign vessels around the Senkaku Islands in the East China Sea.

Japan controls the islands. Its government says they are an inherent part of Japan's territory. China and Taiwan claim them.