Three patients were taken to Altnagelvin hospital on Tuesday night after a crash at around 7.30pm on Victoria Road, Co Londonderry.
The road links Londonderry city to Newbuildings, and the PSNI diverted drivers heading south out of the city along the Prehen Road.
At least one patient was female.
The PSNI described the crash as serious.
There is no confirmation of the patients’ conditions, but it is not believed their injuries were life-threatening.
The crash is understood to have involved two vehicles.