No one has been arrested in connection with a shooting that seriously injured a man in the parking lot of the Scarborough Walmart on Friday night, and Maine Department of Public Safety spokesman Steve McCausland said the investigation continues.

“We don’t expect any new developments (Monday),” he said. “It’s another day of investigation to determine what happened in that parking lot.”

The man wounded in the shooting, Ryan Townsend, 24, of Saco, underwent surgery Sunday at Maine Medical Center in Portland. McCausland was unsure of Townsend’s condition on Monday morning. Prior to surgery, Townsend had been listed in critical condition, McCausland said.

One witness told News Center Maine that a man and a woman were loading groceries into a white pickup truck in the Walmart parking lot around 5:30 p.m. Friday when a man walked up and shot at them.

Lt. Mark Holmquist of the state police told reporters Friday night that the three people involved in the shooting knew one another. He said the pickup truck belonged to the person who shot Townsend. Tyler Hish, 24, of Scarborough was questioned and released following the shooting.

“The shooter, as well as the female passenger that he was with, have been cooperative with the investigation thus far,” Holmquist said.

Walmart was locked down for more than an hour while investigators collected evidence from the scene.