One person is fighting for their life and others are injured after a car struck six pedestrians.
The collision happened in Canvey Island at around 4pm on Saturday.
One victim is in a critical condition and another is described as having suffered a potentially life-changing leg injury.
Both were flown to hospitals in London.
A third person was taken to Basildon and Thurrock Hospital in a stable condition and two others were taken to Southend Hospital in a serious condition.
Ambulance service spokesman Jon Moore said: "The emergency services and critical care teams worked extremely quickly and professionally together at this incident to ensure patients received the right care as swiftly as possible."
Three air ambulances and four ambulances attended the scene, along with a number of police officers.
An eyewitness said: "I was down the front with my family when I saw a woman come running and yelling to her husband to say to come quick because someone had been hit.
"I think it was their child. They bolted it back up and haven't seen them since.
"I then saw the air ambulance land and it caused quite a scene really."
Another person said: "We just came down for the day and heard a bang and then saw all the air ambulances arrive."