A medical plane crashed overnight, killing all five on board, including a young girl en route to a hospital, authorities said. A search helicopter found the wreckage early Monday.

Tracy Smith and her daughter, 15-month-old Lilly Smith, were among those killed, said Peter Olson, a spokesman for the state Department of Public Safety.

Police have not released the identities of the 56-year-old pilot, a 44-year-old male nurse and a 40-year-old female paramedic, pending notification of next of kin, Olson said.

The area where the plane went down is marked by rugged, mountainous terrain; the cause of the crash was under investigation.

The King Air plane was owned by Las Cruces-area Southwest Medivac which, according to the company, has been in business since 1994 and never had a plane go down.

"We've never had anything like this before and hope to never have again," said Rob Campion, a Southwest Medivac spokesman.

He said he could provide no information about the victims.

The twin-engine turbo prop left the Ruidoso Regional Airport about 10:40 p.m. Sunday on a flight to University of New Mexico Hospital in Albuquerque. It crashed almost immediately in Devil's Canyon in the Lincoln National Forest, Olson said.

The search began early Monday, and the plane was spotted about 5:15 a.m., Olson said,

A New Mexico National Guard helicopter called in to help with the search found the wreckage, said National Guard spokesman Maj. Ken Nava.