A Dunkin’ Donuts manager was shot to death early Saturday after a gunman confronted her as she opened the store in North Philadelphia, forced her inside, and demanded she give him all the money, police said.

The victim, a 41-year-old woman, was shot in the head at 5:51 a.m. inside the Dunkin’ Donuts at Lehigh Avenue and Fairhill Street, and was pronounced dead there six minutes later by medics, police said.

Coworkers identified her as Christine Lugo, who lived in the neighborhood and, although she had her own children, was a mother to those she worked with.

“She was an angel, a mother to all of us,” said Larry Evans, one of a few employees who stopped by the restaurant Saturday afternoon to mourn their colleague. “No matter who you are, she give you the shirt off her back.”

The restaurant was closed Saturday, its parking lot and drive-through window cordoned off with tape as police continued their investigation.

In appealing for the public’s help, police Saturday afternoon released a nearly three-minute surveillance video that shows the robbery and provides a rather clear shot of the gunman’s face, along with written descriptions of his clothing.

The man, wearing a blue hooded sweatshirt, gray cargo pants, gray New Balance sneakers, blue gloves, and a blue mask, comes up behind the manager as she is unlocking the store’s front door around 5:23 a.m. Once she opens the door, he grabs her with his left hand while holding a revolver in his right hand and pushes her inside the store.

The video next shows them talking in a supply area, with the manager’s face blurred out. She waves her arms in a pleading fashion as she talks to the gunman, who stands no more than two steps from her, gesturing with the revolver. The footage then shows them in a small office, where the manager is seen seated with what appears to be a cash drawer on her lap. She hands the man an undisclosed amount of money, which he puts in his left pants pocket. He then checks a watch on his right wrist before the video stops, with a freeze-frame of his face, followed by a written description of him: in his late 30s to early 40s, with a stocky build, medium complexion, mustache, and goatee.

Display text says the gunman shot her once in the head and fled the store in an unknown direction. It asks anyone with information to contact the Homicide Unit at 215-686-3334, or call the Police Department tip line at 215-686-TIPS (8477), or send email to tips@PhillyPolice.com, or text PPDTIP (773847).

No one should approach this man but rather call 911, police said.

Police said a $20,000 reward is being offered for information leading to an arrest and conviction.

“All of us at Dunkin’ are saddened to learn of the death of a restaurant manager, and our thoughts go out to her family and friends,” the company said in a statement. “The franchise owner is cooperating fully with the local authorities in their investigation. As this is an active police investigation, we defer any further comment to the Philadelphia Police Department.”

The killing capped an overnight that included three other homicide deaths, including a 16-year-old shot 13 times shortly before 8:30 p.m. Friday at 55th and Market Streets in West Philadelphia. He was part of a double shooting in which a 39-year-old man was hit once in the right leg. The man was in stable condition at Penn Presbyterian Medical Center, police said.

About two hours earlier, a 25-year-old man was shot once in the chest at 10th and Cumberland Streets in North Philly, police said. He was taken to Temple University Hospital, where he was pronounced dead at 7 p.m., police said.

And at 11:38 p.m., police said, a man in his late 20s was shot multiple times while sitting in a vehicle at Broad and Belfield Streets in the city’s Logan section. He was pronounced dead at the scene.

No arrests were reported in any of the shootings.