QUEBEC CITY, Quebec (Reuters) - Forty-three people died on Monday when a bus full of retirees went out of control and plunged into a ravine in rural Quebec, Canadian officials said. "There are 43 dead and five severely injured," coroner Serge Tumel told a news conference. The charter bus had 48 people aboard. Police said the driver was among the dead. The accident, thought by authorities to be the worst in Canada in 30 years, occurred at mid-afternoon on a provincial highway near the small community of St. Joseph-de-la-Rive on the north shore of the Saint Lawrence River, about 60 miles (100 km) northeast of Quebec City. Witnesses said the charter bus appeared to have missed a turn at the bottom of a steep hill. It broke through a guardrail and plunged about 60 feet (20 metres) from the road into a deep ravine. Although the cause of the accident had not been determined, police said brake failure was a leading theory. An autopsy of the driver was also planned. Local residents have long complained that the stretch of highway is particularly dangerous. It was the site of an accident in 1974 in which 13 people died, and Quebec Premier Lucien Bouchard announced on Monday evening there would be an inquiry into the latest crash.