WATSONVILLE, Calif. --
A small plane plummeted into a building that is part of Watsonville Community Hospital and burst into flames Thursday night, and the pilot and three passengers died on impact, aviation officials said.
The pilot was David Houghton, 45, of Santa Cruz. The passengers who died were the pilot's wife Dede Houghton, 44, and their two children, Luke, 12, and Ryan, 10.
David Houghton was attempting to fly his family in his plane from Watsonville to Pine Mountain Lake in the Sierra Nevada for a vacation, his brother said.
The father was CEO of an environmental sciences and engineering company, called A+ Environmental Solutions.
The National Transportation Safety Board said they would not release a cause of the crash until they finish their full investigation. Plane crash investigations by the NTSB can take up to a year to complete.
"We're looking at the man, the machine and the environment," NTSB investigator Michael Huhn said. "There is no air traffic control tower here. It's a non-controlled airport."
Officials raised the death toll Friday morning from two to four when an investigator combing through the blackened wreckage found two children's bodies, Huhn said.
None of Watsonville Community Hospital's patients or staff members were injured. The hospital office wing was unoccupied at the time of the crash.
Luke Houghton, 12, died in the Watsonville hospital plane crash.
The single-engine aircraft went down shortly after it took off from Watsonville Municipal Airport at 7:30 p.m., Federal Aviation Administration spokesman Lynn Lunsford said.
Pilots had low visibility Thursday night because of heavy fog hanging over Watsonville.
Witnesses said the pilot made a sharp U-turn seconds after takeoff and the plane took a nosedive.
The out-of-control aircraft smashed into the clinic's first floor and burst into flames. Firefighters dashed to the scene and extinguished the blaze quickly.
Thomas Arnold, 34, of Watsonville, was in the hospital parking lot when the plane came swooping down just 15 feet over his head, according to the Santa Cruz Sentinel.
"I saw two faces and two big sets of eyes," Arnold told the Sentinel of the plane's passengers. "It exploded when it hit the building."
The plane careened into Coastal Women's Health Care, an obstetrics and gynecology clinic. The clinic is inside a building that is part of Watsonville Community Hospital's complex.
Watsonville Community Hospital is on Airport Boulevard, across the street from the Watsonville Municipal Airport. The airport has two runways and is used mostly by pilots with private small planes like the one that crashed.
The pilot's younger brother, John Houghton, described to KSBW's May Chow the shock he was going through after learning about the horrific crash.
"I spoke to him an hour and a half before he died," John Houghton said. He was supposed to meet David Houghton and his family in the Sierra Nevada for a vacation Thursday night. He became worried when his brother did not arrive.
The pilot's brother searched the Internet and found a news article about a plane crash. "I opened the article and it was my brother's tail number," John Houghton said while holding back tears.
"My brother was a very loving, trusting, enthusiastic person," he said. "I'm taking it pretty hard."
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