The American actor and director George Clooney was treated in hospital in Sardinia on Tuesday after he was injured in a scooter accident. Clooney, 57, had just left his hotel and was heading to a film set on a motorcycle when he crashed into a Mercedes car, news reports said. He was taken to hospital with a possible injury and later discharged from the emergency room with a slight contusion on his knee, state news agency Ansa said. Local police are investigating the accident, Ansa said. Clooney was reportedly thrown from his two-wheeler onto the windscreen of the Mercedes. The John Paul II hospital in Olbia said the Hollywood star was released Tuesday. Local media that had gathered at the hospital said Clooney is believed to have left through a side exit. The actor is in Sardinia to film a miniseries based on Joseph Hellers book "Catch 22", the news agency said. Clooney achieved fame for his part in the medical drama ER. He has since won an Oscar for his role in the movie Syriana in 2006 and for co-producing the film Argo in 2012.