University of Wisconsin Hospital Chief Operating Officer Margaret Van Bree said all Med Flight helicopters had been temporarily grounded as a precautionary measure following Saturday's crash, the La Crosse (Wis.) Tribune said.

Van Bree said the crash appeared to have occurred when the vehicle hit a hill or some trees outside La Crosse. She said pilot Steve Lipperer was killed along with nurse Mark Coyne and Dr. Darren Bean.

The hospital administrator said the crash occurred as the helicopter was returning after delivering a patient at a La Crosse hospital.

Hospital officials told the Tribune the helicopter's owners, Air Methods, will cooperate with the Federal Aviation Administration's investigation into the crash.