A Hawker Hunter plane has crashed at Shoreham Airshow in West Sussex and hit several vehicles, police say.
Sussex Police said there are several casualities, but do not know how many or what condition they are in.
The plane is believed to be in a bush and the A27 is closed in both directions. It is likely to remain that way for the rest of the day.
Eyewitness Stephen Jones said the plane did a loop but did not complete it and crashed.
Other spectators have been told it could be "several hours" before they can leave the area.