FORT COLLINS — Authorities are investigating after a man tried to shoot an officer at a Port of Entry facility in Fort Collins.

Colorado State Patrol Sgt. Mike Baker says the man entered the office at about 7:45 a.m. Sunday, pointed a gun at the officer and pulled the trigger. The firearm did not discharge, and the suspect fled south on Interstate 25 in what was described as a very dirty, white tractor-trailer.

He is between 5-foot-7 and 5-foot-9 with short black hair, a mustache,a medium build and in his early to mid-30s.

The tractor-trailer is reported to have the numbers "4177" behind the passenger-side door. The numbers may be part of a larger number. No other information has been released.