Two men died and two were in a critical condition Friday after a toxic leak in a Suez water treatment plant in the western Czech city of Pilsen. Regional emergency services spokeswoman Maria Svobodova told AFP rescuers were called to treat four unconscious men poisoned by an unknown gas. "They were taken to hospital in a critical condition," she added. "Unfortunately, two people have died," police said in a tweet, adding they were looking into the causes of the leak. The water treatment plant is a unit of the French water company Suez. "I am terribly sorry about the accident," the plant's chief executive Zdenek Horsak said in a statement quoted by the Czech news agency CTK. "We have to find out what exactly happened," he added, offering aid to the affected families. frj/ach