BYRON -- The bodies of two men were recovered from the wreckage of a small plane that crashed in East Contra Costa County on Tuesday afternoon, a Sheriff's Office spokesman said.

The two victims died in the crash, which occurred about 2 p.m. in a field near Marsh Creek Road and Byron Highway, near Discovery Bay, spokesman Jimmy Lee said.

Officials initially said that only the pilot had died but confirmed that a second body was found around 7:05 p.m. The identities of the two men were not expected to be released Tuesday night, pending notification of their relatives.

The plane went down in a field in an area roughly 4½ miles northeast of Byron Airport. It is not yet known if the plane was landing or taking off when it crashed.

Lee said fire crews found the aircraft engulfed in flames upon arrival.

Steve Pease, co-owner of Pease Ranch, said he heard the airplane sputter and then later a big explosion.

He looked out and saw the plane fully engulfed and large plumes of black smoke. All he saw was "a little piece of the tail section."

The plane was a home built, experimental Glasair III, Federal Aviation Administration spokesman Ian Gregor said. Based on a tail number reported in radio traffic, the plane is a two-seat, fixed-wing single-engine plane registered out of Fernley, Nev.

The owner of the plane, who also is believed to be the pilot, also has a landing strip registered in his name in Brentwood.

The crash is under investigation by the FAA and the National Transportation Safety Board, Gregor said.

Paul Burgarino, Kristin J. Bender and Rick Hurd contributed to this report. Contact Matthias Gafni at 925-952-5026. Contact Erin Ivie at 925-847-2122.