U.S. military authorities are investigating reports that two tear gas canisters exploded outside a nightclub near an American base on Okinawa, a military spokesman said today. The incident was the latest in a series of mishaps to plague U.S. military forces in this country. On Friday, the commander of a U.S. destroyer was relieved of his post after practice shells from his ship reportedly missed hitting a Japanese vessel by 330 yards. Japan lodged a protest over the Nov. 9 incident off Boso Peninsula east of Tokyo. Frederick H. Michaelis Jr. was relieved of command of the guided missile destroyer USS Towers and transferred to Destroyer Squadron 15, military spokesman Rodriguez said. In October, rifle bullets struck a civilian housing area near a firing range on Okinawa. Earlier this month, two Marine helicopters collided in flight over the southern island, killing four servicemen. About 46,000 U.S. troops are stationed in the country under the U.S.-Japan mutual security pact. No injuries or damages were reported in the latest incident in Okinawa, Marine Master Gunnery Sgt. Jake Rodriguez said, but the blasts sent scores of crying, choking people into the streets late Saturday. Little else was known about the incident, Rodriguez added. ``Marine Corps officials acknowledged reports of an apparent release of two CS gas (tear gas) devices in the vicinity of Club Larosa, Chatancho,'' a statement from the U.S. military in Japan said. The residential neighborhood in Chatancho borders the U.S. Kadena Air Base. Military authorities and Japanese police were investigating fragments from the exploded devices to determine their origin and composition.