Four people died Sunday after their medical helicopter crashed inside Sam Houston National Forest in Texas, officials said.

The PHI Air Medical team was based at Coulter Field in Bryan, Texas, the Houston Chronicle reported.

The company that owns the private air ambulance identified three dead crewmembers as pilot Charles Wayne Kirby, flight nurse Jana Bishop and flight paramedic Stephanie Waters.

The identity of the 58-year-old male patient who died in the crash was not released.

"The helicopter was totally disintegrated upon impact," said Department of Public Safety Trooper John Sampa. "It took down a couple of pine trees."

The helicopter was a Bell 407. It went down about 2:45 a.m. in a desolate area of the forest, while en route to Houston, the newspaper said.

Investigators from the National Transportation Safety Board were working to determine the cause of the crash.

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