Gunfire erupted outside a popular Railroad Square restaurant Thursday night, followed quickly by police officers who descended on the area in search of an elusive gunman.

The action began around 8 p.m. with a report of shots fired in the parking lot of the Chevy's restaurant. No one was hit, and a suspect was reported to have fled north along the railroad tracks, according to Sgt. Josh Ludtke.

Police converged on the nearby Stark's Steakhouse a short time later as a helicopter circled overhead shining its spotlight on streets, businesses and backyards. Officers were seen combing the area around and behind the Adams Street eatery.

They briefly detained a young man on the sidewalk outside the restaurant, but he was later determined not to be the suspect, Ludtke said.

Sylvie Vatinelle, 45, was celebrating her birthday at Chevy's when the shots were fired.

"Dinner just ended with a bang, literally," she said as she waited for her car to be released from an area of Fourth Street cordoned off by police.

Her car was parked next to a newer, white, full-size Ford pickup that had its driver side window shattered, apparently by gunfire.

Her brother-in-law, Keith Jones, 45, said he was inside Chevy's near the entrance when he heard several shots fired.

"It was like BANG! BANG! BANG! It definitely sounded like a gun," Jones said.

Police say the shooting appears to have been the result of an argument between two groups, though they did not characterize the nature of the dispute.

As of early Friday morning, officers still had not located the gunman.