© The Associated Press/Samantha Clemens/The Spectrum
Emergency officials respond to a fatal plane crash near the St. George Municipal Airport on Saturday, May 26, 2012, in St. George, Utah.
St. George, Utah - A small plane that crashed early Saturday at a municipal airport in southern Utah killed all four people on board, authorities said.

The downed single-engine Cessna 172 was found at about 6 a.m. some 400 feet from the runway, said Marc Mortensen, assistant to the St. George city manager. It's uncertain whether the crash occurred shortly after takeoff or upon landing, he said.

The plane crashed under "unknown circumstances," Federal Aviation Administration spokesman Ian Gregor said.

Although the area saw windy conditions on Friday and later Saturday, there was no severe weather at the airport during the early morning hours on Saturday, National Weather Service meteorologist Monica Traphagan told The Spectrum of St. George.

The airport has been in operation at its current site for about 1½ years. It does not have a radio tower and pilots use an automated system to communicate with one another when landing or taking off, Mortensen said.

The wreckage was found by an airport crew making a routine safety check of the property. The city expected to release the victim's names either late Saturday or Sunday, Mortensen said.

Federal authorities were investigating the cause. It normally takes the National Transportation Safety Board months to come up with a probable cause for crashes.

Source: The Associated Press