A rescue team was a special away team comprised of Federation Starfleet personnel in an event that an away mission was required to rescue potential survivors from a previous away mission. Occasionally, multiple rescue teams were deployed for the same rescue mission.
After the Delta Flyer ran into multiple ion storms and crash landed on the surface of a M-class planetoid in 2375, Voyager deployed rescue teams to find the Delta Flyer crew. Rescue team alpha led by Chakotay asked Seven of Nine for data on the caverns near the crash site. (VOY: "Once Upon a Time")
Later that year, Voyager rescue teams stood ready to assist a badly damaged vessel – the Silver Blood Voyager – but it had been reduced to an unidentifiable field of debris by the time the ship arrived. (VOY: "Course: Oblivion")