Road closures are in place from the A404 Bisham Roundabout to the Pinkneys Drive junction on the A308.
A flatbed lorry is stuck in the hill on the A308 just off the roundabout and there is a fuel spillage.
There are worries that the fuel may have gone into the water course.
Two cars have also left the road.
Thames Valley Police are currently attending.
UPDATE Wednesday, July 2, 9.20am:
The A308 Marlow road was still shut this morning following an oil spill near the Bisham Roundabout
The spillage is believed to be oil and it is not thought to have come from a vehicle
A spokeswoman from the Royal Borough confirmed that members of their street team attended the oil spill at about 5pm yesterday and were there until the early hours of this morning.
She said they tried to clear the spill with chemicals but have had to put down an asphalt-like absorbent on the road.
The road is still shut and the Royal Borough is working with Thames Valley Police to find out when the road can be safely reopened.
This is likely to be later today.
The A308 has now reopened following an oil spill yesterday afternoon. It will be shut again briefly tomorrow at about 11am while the road is swept.
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