SOUTH BEND, Ind. (AP) — A private jet apparently experiencing mechanical trouble crashed Sunday in a northern Indiana neighborhood, hitting three homes and killing two people aboard the plane, authorities said.

The Beechcraft Premier I twin-jet had left Tulsa, Okla.'s Riverside Airport and crashed late Sunday afternoon near South Bend Regional Airport, Federal Aviation Administration spokesman Roland Herwig in Oklahoma City said. Two of four people aboard the plane were killed, Herwig said.

It was not clear if anyone on the ground was killed, and Herwig did not have any additional information.

South Bend Memorial Hospital spokeswoman Maggie Scroope said three people injured in the crashed were being treated there; one was in serious condition and two were in fair condition. Scroope did not know if they were on the plane or the ground.

The plane was registered to 7700 Enterprises of Montana LLC in Helena, Mont. The company is owned by Wes Caves and does business as DigiCut Systems in Tulsa, Okla. It makes window film and paint overlay for automobiles.

A woman identifying herself as Caves' wife answered the phone at their home Sunday and said, "I think he's dead," before hanging up.

In South Bend, Assistant Fire Chief John Corthier said everyone on the plane and in the first house struck by the jet had been accounted for four hours after the crash. That wasn't true of the other two houses, and Corthier couldn't say how many people they were still trying to track down.

"We absolutely don't know," Corthier said, adding that the presence of jet fuel and structural damage made the scene "very dangerous" for investigators. The aircraft remained lodged in one of the homes late Sunday.

"We have to shore up the house before we can enter the house," he said.

Investigators from the FAA and National transportation Safety Board were expected to arrive on the scene Sunday night, Corthier said.

Part of the neighborhood southwest of the airport was evacuated after the crash, and Corthier said it was possible some residents would be allowed back into their homes Sunday night.

Electricity was cut off to part of the neighborhood.

Mike Daigle, executive director of the St. Joseph County Airport Authority, said the jet attempted a landing about 4:15 p.m., went back up and maneuvered south to try another landing, but eight minutes later the airport learned the plane was no longer airborne.

"There was an indication of a mechanical problem," Herwig said.

Stan Klaybor, who lives across the street from the crash scene, said the jet clipped the top of one house, heavily damaged a second, and finally came to rest against a third. Neighbors did not know if a woman living in the most heavily damaged house was home at the time, and a young boy in the third house did not appear to be seriously injured, Klaybor said.

"Her little boy was in the kitchen and he got nicked here," Klaybor said, pointing to his forehead.

His wife, Mary Jane, regularly watches planes approach the airport.

"I was looking out my picture window. The plane's coming, and I go, 'Wait a minute,' and then, boom," she said.

"This one was coming straight at my house. I went, 'Huh?' and then there was a big crash, and all the insulation went flying," she said.