A security guard at Christmas Village in LOVE Park has been charged with murder in the death of a man police say he shot during an argument Tuesday night.

Police say Gregory Thomas Sr., 43, of the 2600 block of Wilder Street in Grays Ferry, fatally shot Ryan Groff, 29, of Lancaster.

Just before the shooting, Thomas tried to stop Groff from attempting to enter an off-limits area of the park, which is being readied for the Christmas Village to open on Thanksgiving Day, city officials said at a news conference Wednesday.

Thomas argued with Groff, then went to his Jeep, retrieved a handgun, and shot him at least twice, said Chief Inspector Frank Vanore.

Officials said Thomas worked for a private contractor hired by the Christmas Village organization. He did not have a permit to carry a gun as part of his duties, Mayor Jim Kenney said.

German American Marketing Inc., owner of Christmas Village, extended condolences to Groff’s family Wednesday and said it was cooperating with law enforcement and reevaluating security at the site. “We are dedicated to providing a safe and welcoming experience and have done so for over a decade,” the company said in a statement. “We contract with a private security company and have done so every year.”

After the shooting at 8:40 p.m. in the park near the intersection of 15th Street and JFK Boulevard, Thomas drove home, police said. A supervisor from his workplace later went to his home and took him to police headquarters at Eighth and Race Streets, where he turned himself in, police said.

Police officers responding to a report of the shooting found Groff on the ground suffering from multiple gunshot wounds and took him to Thomas Jefferson University Hospital, where he died just after 9 p.m. Tuesday.

The slaying in the heart of the Center City business and shopping district drew quick response from police officers who were working a construction detail nearby.

Police Commissioner Danielle Outlaw said detectives recovered surveillance video that helped police identify several witnesses who were on the scene at the time of the shooting.

The speed of the arrest in the case stood in contrast to the department’s overall record of solving fatal shootings. Police have made arrests in less than 30% of the homicides so far this year, which is on track to be the deadliest 12-month span in city history.

As of Wednesday morning, there had been 473 homicides, up 11% from the same time last year. Last year, there were 499 slayings in the city, one fewer than the city’s all-time record of 500 in 1990.