A Palo Alto man died and his wife was seriously injured in a small plane crash Monday in South Lake Tahoe, authorities said.

The single-engine Mooney M20C went down in a wooded area east of the South Lake Tahoe Airport at about 11:10 a.m., said Lt. Pete Van Arnum of the El Dorado County Sheriff’s Office. Witnesses said the plane lost altitude after taking off from the airport and banked sharply before crashing.

The plane hit some large pine trees and flipped over, Van Arnum said.

The male pilot, Steven A. Lefton, 67, of Palo Alto, was killed in the crash, Van Arnum said. His wife, Karen, the only passenger, suffered moderate injuries and was pinned in the wreckage.

Beth Frisby, an off-duty California Shock Trauma Air Rescue flight nurse, was walking her dog in the area and came upon the scene. Van Arnum said she provided medical aid and comfort to Karen Lefton for several minutes until sheriff’s deputies, medics and firefighters from the Lake Valley Fire Department arrived.

Fuel leaking from the plane was doused with fire retardant and Karen Lefton was removed from the wreckage, Van Arnum said. She was then airlifted to Renown Regional Medical Center in Reno.

The Mooney M20C was manufactured in 1963 and belonged to Steven Lefton, according to records maintained by the Federal Aviation Administration. The model has four seats and a top speed of about 127 mph.

On his LinkedIn profile, Steven Lefton listed his occupation as director of power plant projects at Intertek-Aptech in Sunnyvale. He graduated from the University of Kansas with a bachelor’s of science in chemical engineering in 1969.

No one answered the phone at the couple’s residence on the 4200 block of Manuela Drive.

The Federal Aviation Administration and National Transportation Safety Board are investigating the crash, according to FAA spokesman Ian Gregor. A preliminary report is expected within two weeks.

Email Jason Green at jgreen@dailynewsgroup.com; follow him at twitter.com/jgreendailynews.