A driver involved in a fiery crash that killed the driver of a tractor-trailer on I-485 in northeast Charlotte Friday morning is being sought. The incident happened before 10 a.m. on I-485 outer at Exit 21, closing the interstate between I-77 at W WT Harris Boulevard and sending a plume of smoke into the air. Troopers say a tractor-trailer was traveling south on I-77 and merging when a passenger vehicle on the outer loop attempted to merge onto the ramp, hitting the tractor-trailer on the left side. The collision caused the tractor-trailer to travel off the right shoulder, hit a concrete apron and strike a bridge pillar. The truck engulfed in flames, killing the driver, troopers say. The other driver involved got out of their vehicle and took off, troopers say. Police K9 and a helicopter are being used to locate the driver.