A man has been arrested on suspicion of attempted murder after he and a woman were seriously burnt in a fire within a garden.
Essex Police are investigating whether the blaze in Boyce Green, Benfleet, was a deliberate act.
The man, aged in his 50s, and a woman in her 70s were airlifted to Broomfield Hospital in a critical condition.
Officers had received reports of a disturbance at about 10.50am on Tuesday and the man was arrested at the scene before he was taken to hospital.
Senior investigating officer DCI Daniel Stoten, of Kent and Essex's serious crime directorate, said it appeared to be an isolated incident with no wider risk to the public.
"We understand there were a number of people in the area, including golfers at a nearby golf club," he said. "If you were in Boyce Green or on the golf club between 6am and 11am, then we would like to hear from you."
Anyone with information is asked to call Essex Police on 101 quoting incident 311 of 13/03 or Crimestoppers anonymously on 0800 555 111.