A 4th Oxygen SOS was sent by Sir Ganga Ram Hospital in Delhi late on Saturday night. The hospital said it had medical oxygen left to last only about 45 minutes to an hour. Later, the oxygen tanker arrived at Sir Ganga Ram Hospital at 4:15 am on Sunday. Doctors and nurses had started manual ventilation in Ganga Ram Hospital, till at least one tanker arrived at the facility. Gandhi Hospital in Delhi's Uttam Nagar also sent out an SOS for oxygen, saying they had about an hour's supply of oxygen left. The lives of over 100 patients were at risk, sources have said.