Philadelphia authorities on Monday urged potential witnesses to speak up and help identify the man who fatally shot a Dunkin’ store manager early Saturday in the city’s Fairhill section.

Chesley Lightsey, homicide chief in the District Attorney’s Office, asked the public to review the “very clear” surveillance video of the suspect from inside the store that police posted on YouTube and help them determine who shot Christine Lugo after robbing the store on the 500 block of Lehigh Avenue around 5:30 a.m. Saturday.

“We are begging you to come forward,” Lightsey said. “The only way the police can get to an arrest and then our office can get to approve charges is for the community to come forward and help.”

Mayor Jim Kenney, at an unrelated news conference, said the video showed Lugo trying to comply with the robber’s demand, “and he still killed her.”

“There’s a bunch of different types of violence that we’re dealing with,” Kenney said. “This is a vicious robbery and killing.”

The slaying left Lugo’s relatives and coworkers devastated, with her children telling 6ABC that her eventual goal was to move to Massachusetts to be with them and her grandchildren. Attempts to reach family members Monday were unsuccessful.

The store where she worked was closed Monday, with signs saying employees were mourning “the loss of our beloved manager Christine Lugo.” A photo of her hung in the store window, while dozens of candles and stuffed animals were placed beneath balloons out front.

The slaying was one of at least six between Friday and Sunday, according to police. Already this year, 228 people have been killed in homicides, police said, by far the highest year-to-date total since at least 2007, and 33% higher than at this time last year.

In addition, 889 people have been shot in the city through Sunday, according to police statistics — a 28% increase compared to last year’s pace.