PARIS, April 1 (Xinhua) -- Four people have died and dozens became ill after eating contaminated food in a retirement home in the southwestern French city of Lherm, local authorities said Monday.

"Twenty-two residents of the residential care facility for dependent elderly people ... were reported to have been victims of food poisoning on the evening of March 31 after dinner," according to a statement released by Haute-Garonne prefecture.

An investigation is underway to determine the cause of the food poisoning, the statement said.

No further details were given on the victims.