A Denver police officer who was shot and killed while trying to break up a fight has been remembered as a devoted single mom and a fiercely dedicated officer who wanted to make the world safer for her 12-year-old daughter. More than 2,800 people -- uniformed police officers, family members and friends -- packed Denvers First Church of the Nazarene Saturday for the funeral of Celena Hollis who was shot in the head on June 24. She was 32. Hollis was off-duty but in uniform providing security for a free jazz concert in City Park when she was shot. Police arrested 21-year-old Rollen Oliver on suspicion of first-degree murder.Reverend Doctor E. Christopher Hill gave an emotional sermon as he talked about Hollis."Her momma told me that even though she died at some 32 years of age, that in 32 years she lived more than most people. She worked overtime so she could get good vacation, and if she wanted a nice pair of shoes, baby she'd get some details together and work it out." Hollis' daughter, Amyere, sobbed as she recalled how her mother was like a second mom to many of her friends. Hollis was a seven-year veteran of the Denver force and worked as an officer in Detroit before that. About a dozen Detroit officers who worked with her attended the service.After the funeral service, a procession of police cars from across the country drove to Fairmount Cemetery. The streets along the route were filled with people, all who told 7NEWS they had their own reasons to come out.Kristin Kobus said she wanted, "to pay my respects to officer Hollis and her family. Thank her for everything she's done. What a hero she is, and the entire community thanks her."Penny Morning stood in the bike lane thanking each police department as they passed.Morning said she wanted to show support and that was the general consensus from the crowd."I talked to people over here and standing around and they said they wouldn't be no where else on a Saturday," said Morning.Even at six-years old, little Braden knew what Saturday was about as he waved his flag and said, "We're all here to celebrate her."As for the Denver Police Department, officer Anthony Wilkerson asked all who wear the badge to keep Hollis' work ethic alive."Serve your community with integrity, honesty and unity. Strive to be like Celena for she truly is Denver's finest," Wilkerson said.