River Bann searched for missing man
Four rescue teams are searching the River Bann close to Kilrea after reports that a man got into difficulty in the water.
About 40 people joined in the search near the Bann Road bridge in the County Londonderry village after the alarm was raised at 18:00 BST on Saturday.
Sean McCarry from the Community Rescue Service said canoeists saw the man struggling and raised the alarm.
"We are now conducting a major search," he said.
The police helicopter was also at the scene.
Mr McCarry said that he understood that an attempt had been made to rescue the man, but it failed.
"Somebody tried to help him but had to go back to the bank," he said.
"We now have four teams at the river - community service boats and crews are on the river."
Police said a man was seen jumping into the river.
They want to speak to a group of young men who left the area in a red car a short time later.
They have appealed for witnesses to come forward.