YT understands that a pedestrian has been knocked down by a bus in Grays.
The incident, at just after 2.20 pm, is believed to be on Crown Road just at the level crossing close to the shopping precinct.
Emergency services are there.
A spokesperson for Essex Air Ambulance Service said: "The ambulance service sent an ambulance crew, rapid response vehicle and Essex Air Ambulance to a road traffic incident in Crown Road, Grays.
"They treated a woman in her 20s who had a head injury and suspected concussion.
"She was taken to Queens Hospital for further treatment.
