An air ambulance (search) crashed, killing three people, and the sole survivor was rescued after calling authorities on his cell phone and guiding them to the wreckage by describing the sirens and other sounds he could hear.

Timothy Baldwin, 35, a medic, spent about 90 minutes on his cell phone directing rescuers to the site. He then waited 21/2 hours more after his battery died.

The plane went down in snow and fog Tuesday night while on its way to pick up a victim of an automobile accident. The pilot and two medics were killed.

Rescuers had difficulty tracing the plane's emergency transmitter and had to rely on Baldwin's description of the sirens and train whistle he could hear to figure out whether they were getting closer to the wreckage.

"It's like looking for a needle in a haystack," Carbon County (search) Sheriff Jerry R. Colson said. "A lot of country, a lot of tough country to cover."

Baldwin had to be pried out of the plane, and reached the hospital early Wednesday in critical condition.

The cause of the crash was under investigation.

Although the plane crashed just 31/2 miles from the airport, rescuers did not reach it for four hours because it had gone down in the middle of rough, snow-covered prairie.

"The snow was real hard, and people were getting stuck," airport manager Dwight France said.