The multi-engine, propeller-driven plane struck the small homes a few blocks from Tweed New Haven Airport as it went in for a landing.
National Transportation Safety Board investigator Robert Gretz said Friday night there were casualty reports of two or three people in the plane and two or three on the ground. He said local and state authorities were at the scene looking for victims.
Soon after the crash, officials had said at least three people were missing: the pilot and two children, ages 1 and 13, in one of the houses. Gov. Dannel P. Malloy later said the plane also may have been carrying two passengers but officials were still trying to verify whether that was true.
East Haven fire Chief Douglas Jackson said Friday afternoon: "We haven't recovered anybody at this point, and we presume there is going to be a very bad outcome."
Less than two hours later, Malloy said rescuers had spotted two bodies, including one of an adult, but hadn't recovered them. The plane's fuselage had entered one of the houses, and the recovery effort was focusing on the home's basement, he said.
Mayor Joseph Maturo said later that the houses were still unstable and crews had not completed a full search.
The plane, a Rockwell International Turbo Commander 690B, flew out of Teterboro Airport in New Jersey and crashed at 11:25 a.m., the Federal Aviation Administration said.
Tweed's airport manager, Lori Hoffman-Soares, said the pilot had been in communication with air traffic control and hadn't issued any distress calls.
"All we know is that it missed the approach and continued on," she said.
A neighbor, David Esposito, said he heard a loud noise and then a thump: "No engine noise, nothing."
"A woman was screaming her kids were in there," he said.
Esposito, a retired teacher, said he ran into the upstairs of the house, where the woman believed her children were, but couldn't find them after frantically searching a crib and closets. He returned downstairs to search some more, but he dragged the woman out when the flames became too strong.
Wilson Idrovo said he was working on a house nearby when his son said: "Daddy, the airplane is falling down."
Idrovo said he went into the house but couldn't get into a room where the plane had crashed.
"I feel so bad," he said.
Angela Wordie was on her deck taking in towels when she noticed a plane making a strange sound.
"It kind of was gliding," she said. "The next thing I know it hit the house."
Another neighbor, Pablo Arenas, said he and his neighbors live in fear of the planes. He said some pilots appear to be novices in training, while others said planes often fly low and larger aircraft have begun using the airport in recent years.
Maturo, the mayor, said a priest was with the woman whose children were feared dead, and he offered sympathy to the family.
"It's total devastation in the back of the home," he said.
Neighbors said the woman moved into the neighborhood recently.