Witnesses told police a Chevrolet Blazer was traveling north on I-469, north of U.S. 30, when the driver appeared to lose control of the vehicle, New Haven police spokesman officer Scott Adam said.
Adam said the vehicle moved from the left lane to the right lane, went off the road and rolled several times. It came to rest upside down at the bottom of a long, steep embankment.
First responders were dispatched about 3:45 p.m. At the scene, they found that a man, possibly the driver, had been ejected. A woman was sitting outside the vehicle, and two young children were trapped inside, Adam said.
One child was quickly removed from the Blazer. It took 27 minutes for firefighters to extricate the second child, Adam said.
The four were taken by helicopters to a hospital. One child was in critical condition. The woman and the other child were in serious condition. The man died after arriving at the hospital, Adam said.
The names of the four were not released. Police did not know how they were related.
Adam said a mechanical problem may have caused the crash, which remains under investigation.
The northbound lanes of I-469 were closed to traffic after the crash until about 7 p.m.