Emergency services responded to a major incident on the River Foyle on Saturday after 26 people became stranded in the water.
It is understood two boats participating in a fundraising event for the YMCA got into trouble at about 2pm on the stretch of river between Maghermason in Co Tyrone and Carrigans in Co Donegal.
Six people were taken to hospital by helicopter for treatment as a result of the incident and the remainder received treatment from Northern Ireland Ambulance Service staff at Prehen Boat House.
A spokesman for the ambulance service said 26 people were rescued.
The Irish Coastguard took six people directly to Altnagelvin Hospital in Derry by helicopter.
The other 20 were taken to shore by Foyle Search and Rescue and the police where they were assessed by paramedics before being transferred to Altnagelvin.
Sinn Féin MLA Maeve McLaughlin praised the efforts of the emergency services.
“Their swift efforts and team work in responding to this major incident are to be applauded,” she said. “Hopefully all of those involved in this incident will make a full and speedy recovery.”
SDLP MLA Mark H Durkan said: "It has been a cold day and the water in the river would have been freezing. Coupled with the strong current and high tide it is extremely fortunate that we did not witness a tragedy here today."