A boat carrying maritime rescuers who set off to help a fishing boat in trouble in wind-whipped waters off the western coast of France has overturned, killing three people.

The prefect of the Vendee region said that the four other people in the rescue boat Friday morning are safe but that the fishing boat has yet to be found.

Benoit Brocart said three helicopters are flying over the area off Les Sables d'Olonne, off the Atlantic coast of France, and dozens of rescue workers are searching for the fishermen.

Wind gusts have been measured at up to 120 kilometers per hour (75 mph) on Friday, and the National Society of Sea Rescue, which sent out the boat, had warned on Twitter to avoid coastal regions.