Four Gulfstream employees Kent Crenshaw, Vivan Ragusa, David McCollum, Reece Ollenburg, killed after test aircraft rolls over and crashes in a fireball

ROSWELL, N.M. -- Gulfstream has identified the four Georgia employees killed in a fiery crash of a test twin-engine luxury business aircraft at a southe New Mexico airport.

Officials with the Georgia-based plane company say the four who died Saturday were test pilots Kent Crenshaw, 64, and Vivan Ragusa, 51; and technical specialists David McCollum, 47, and Reece Ollenburg, 48.

They were from Savannah, where the company is based.

The team aboard the Gulfstream G650 was conducting takeoff-performance tests at Roswell Inteational Air Center at the time of the crash, the company said.

The National Transportation Safety Board is investigating the cause.

Gulfstream reportedly began taking orders on the nearly $60 million G650 jets in April 2010, with delivery expected next year.

Federal Aviation Administration spokesman Lynn Lunsford said the plane had just taken off when it rolled and slammed into the runway. He said the plane's gear collapsed and the craft burst into flames.

"We mou the loss of our colleagues and friends, and extend the deepest sympathies to their families," said Joe Lombardo, president of Gulfstream Aerospace Corp., a subsidiary of General Dynamics.

Lombardo said the company was cooperating with the investigation.

Crenshaw joined Gulfstream in August 1997. He is survived by his wife and son.

Ragusa, who is survived by his wife and three children, was hired by the company in 2007.

McCollum, who went to work for Gulfstream in 2006, is survived by his parents.

Ollenburg went to work for the company in June 2009. He is survived by his wife and three children.