The Waterside-bound lane of the Foyle Bridge has been closed following suspected oil spillage and road traffic collision.
The PSNI in Derry have asked people to avoid the area if possible.
"Foyle Bridge from cityside to Waterside currently closed due to a road traffic collision and slippery substance on the road surface," the force confirmed.
"Roads Services have been informed. Please find an alternative route," the PSNI said.