Emergency services were called to two accidents on the stretch of road in the space of an hour.
In the first, just before 6.30am, a car travelling northbound left the road opposite Shiremark Farm and overturned into a ditch.
The driver and passenger escaped unhurt.
In the second incident, at about 7.10am, a car driven by a 29-year-old woman crashed into a garden at Myrtle Cottages, police said.
Sussex Air Ambulance was called and airlifted a three-year-old girl, who was a passenger in the car, to St George’s Hospital in London.
A Sussex Police spokesperson said there is a possibility of a diesel oil spillage in the area, and motorists have been advised to take care on the road.
Officers are investigating the cause of both collisions.
There is also some traffic congestion in the area.
Police are appealing for anyone with information about either incident or the condition of the road to contact them.
You can email [email protected] or phone 101, quoting serial 156 of 10/10 concerning the collision at 6.24am and serial 178 of 10/10 concerning the collision at 7.09am.