1050 Chennai, May 5 At least 11 patients died at the Government Chengalpattu Medical College Hospital here on Tuesday night. An inquiry has been ordered into the cause of death. Though it is alleged that the patients died due to oxygen shortage, senior officials said it is not the case as the hospital has sufficient stock. "As per initial reports, the hospital has sufficient stock of oxygen. It is not an oxygen supply issue. Only an inquiry would reveal as to the cause of death," J. Radhakrishnan, Health Secretary told IANS. He pointed out there are several other patients who were on oxygen supply and they were not affected.