A fishing vessel has sunk off the Western Isles in Scotland.
Three of the four crew members are missing, the Maritime and Coastguard Agency has said.
The coastguard received a distress alert just before 3.45am on Saturday, and the vessel's emergency positioning beacon was activated near Mingulay.
One of the crew was rescued and taken to hospital by helicopter. The crab-fishing vessel was based in Lewis, a spokesman for Barra RNLI said.
A Maritime & Coastguard Agency spokeswoman said the vessel went down in relatively calm weather conditions.
She said: "The coastguard search and rescue helicopter based at Stornoway has been searching the area along with the Barra RNLI lifeboat.
"The lifeboat remains in the area and the coastguard search and rescue helicopter from Prestwick has taken over so the search can continue."
A Marine Accident Investigation Branch (MAIB) spokesman said: "The MAIB has deployed a team to conduct an investigation."
The average sea tempeartures around the Western Isles are 6-8°C.
According to the US Search and Rescue Task Force cold water survival manual, the expected survival time in such temperatures is 1-3 hours, with exhaustion or unconsciousness setting in within 30-60 minutes.
Additional reporting by agencies
