Part of the Long Island Expressway in Syosset was closed for 12 hours starting early Thursday morning following a tractor-trailer crash.

A vehicle cut off the truck, driven by Richard Forenza, 40, of Westbury, causing him to lose control, strike the center median and flip over catching on fire near the eastbound side of the road near the South Oyster Bay Road exit at 4:45 a.m., according to 2nd Squad detectives.

The truck then struck a sport utility vehicle driven by Mark Ndreca, 33, of the Bronx, who suffered burns to his body and was taken to Nassau University Medical Center in serious condition for treatment.

The expressway was fully reopened after 5 p.m.