Sligo-based Coast Guard helicopter Rescue 118 assisted in a major multi-agency operation on Lough Foyle this afternoon which saw four people rescued from the water.
Just after 2pm, the alert was raised by the activation of a personal locator beacon when a 30-foot fishing vessel overturned.
The Maritime Rescue Sub Centre in Malin Head, Belfast Coastguard, Portrush Lifeboat and other local craft also assisted in the rescue operation.
The four casualties were located and recovered by the Greencastle Coast Guard Unit and transferred to hospital by Rescue 118.
The casualties are being treated at Altnagelvin Hospital as a precaution.
