Update 10.20pm: The search for a man missing off the coast of Dublin will resume from first light tomorrow morning.
RNLI lifeboats and local fishing trawlers, along with the Irish Coastguard helicopter, are all involved in the search effort.
Eoin Medland of the RNLI said: "We now have a multi-agency effort, Skerries lifeboat recovered one of the casualties and as I say, every effort is ongoing in the search," he said.
Update 5.43pm: The fisherman rescued off the Dublin coast was said to be conscious when he was brought ashore about half an hour after the alarm was raised.
He was rushed to hospital for treatment.
The local RNLI lifeboat crew in Skerries was the first rescue boat on the scene and later supported by teams from Howth and Clogherhead.
The Navy ship LE Orla was also in the area to co-ordinate the search and rescue mission along with the Dublin-based Irish Coast Guard helicopter.
A spokesman for the Irish Coast Guard said: "A number of other boats are in the area as well."
The men were believed to be on a small local vessel involved in razor fishing.
It is understood a doctor and an advanced paramedic were on the scene when the rescued fisherman was taken from the water. He was treated on the shore before being taken away in an ambulance.
The Garda Water Unit was later dispatched to the scene.
Others taking part in the mission included the Navy vessel LE Niamh and the Air Corps' Casa maritime patrol aircraft.
Earlier: The Irish coastguard says a search is underway for a crewman after a small fishing vessel sank off the coast of Dublin, with two people on board.
One person has been rescued and a search operation is underway for the second person.
The Marine Rescue Coordination Centre say the recovered crewman was brought ashore and handed over the HSE ambulance service.
It is understood the RNLI and coastguard units are involved in the search. The vessel, which is understood to have been local, went down about 100m from Skerries harbour in north Dublin. Howth RNLI was alerted around 2pm.