Why did private plane crash into Conn. neighborhood?

(CBS News) In Connecticut, federal investigators are trying to learn why a private plane crashed into two homes near New Haven Friday. The wreckage was so tangled that it took first responders hours to recover four bodies.

Parts of the twin-engine airplane remain visible in the charred wreckage.

Inside one of the houses, the bodies of a 13-year-old girl and her 1-year-old sister.

The two other victims are the pilot, former Microsoft executive Bill Henningsgaard, from Seattle, and his teenage son, Maxwell.

This was Henningsgaard's second aviation accident. In 2009, he cheated death when he crash-landed in the Columbia River. He was not as fortunate this time.

Friday's accident occurred shortly before noon.

"A woosh of air come down, and I felt the ground shake, and I heard the explosion," Joe Euskozitz said.

Neighbors heard the girls' mother screaming for help, but the intense flames forced rescuers back.

"It was smoke; it was like blue-flame smoke coming from the house," said Monique Hawley, "and I just- it's fear."

This is one of a half-dozen accidents over the past two years in which a plane crashed into houses near an airport.

"In our major cities, the airports are close to populated areas, so it's important to have good communication with air-traffic control to take the necessary precautions," said Kitty Higgins, a former board member with the National Transportation Safety Board, "but I don't think the airport per se or the location of the airport per se is the issue."

But some East Haven residents are having second thoughts.

"When I bought this house, would this ever happen? They say, 'no, it'll never happen,'" said Curt Samuels. "It happened."

The other house hit was vacant at the time. According to relatives, the Henningsgaards were in the process of visiting eight prospective colleges and were on their way to see Yale University in New Haven.