Update, 1:20 p.m. The northbound lanes of Interstate 95 in Darien have been reopened.
Update, 11:55 a.m.: State Police report the accident caused two fatalities.
At the scene, Trooper Matthew Satkowski said the accident occurred when a Dodge Caliber SUV on the right shoulder pulled out and struck a tractor-trailer traveling in the right lane. He said the SUV then swerved left, struck the center median, and then was "t-boned" by the truck.
Satkowski said there were four females in the SUV and two people in the truck tractor.
He said it would take several hours to clean up the debris and spilled diesel fuel.
Update, 11:30 a.m.: A tractor-trailer overturned and at least one passenger vehicle was involved.
The state's transportation department says there are extensive delays on I-95 between exits 4 and and 9. There are also severe traffic delays on local roads in Darien.
Update, 11:15 a.m.: State Police say at least two people have died as a result of this fiery crash. The northbound lanes of I-95 remain closed between exits 9 and 10.
Update, 10:07 a.m.: State transporation officials say the fatal tractor-trailer accident in Darien now has backed up northbound traffic on Interstate 95 to Exit 5 in Old Greenwich/Riverside.
Update, 9:15 a.m.: Connecticut State Police have confirmed that Saturday morning's tractor-trailer accident on I-95 North in Darien was fatal, according to NBC Connecticut.
Details, including the number of deceased and the extent of other injuries, were not immediately available.
An early morning accident involving a tractor-trailer has shut down I-95 north in Darien, snarling traffic for up to three miles.
According to the Connecticut Department of Transportation, the crash occurred around 6:13 a.m between exits 9 and 10. As of 8:30 a.m., northbound congestion had reached back to exit 6 in Stamford.
The left lane of I-95 south was also closed shortly after the accident as emergency responders work to clear the wreck, causing a smaller backup in the opposite direction.
The is on the scene.
Patch will have more on this story as information becomes available.