Hollis was shot and killed at last week's jazz festival while trying to break up a fight. Rollin Oliver, 21, has been arrested in connection with her murder.
"We won't back down and we will not surrender," Hancock added. "This is our city."
Since Hollis was murdered on June 24, city officials have urged residents to continue attending City Park Jazz. Today, councilman Albus Brooks asked Denverites to "make a statement and show up." Officials further asked that attendees wear purple, Hollis's favorite color. Volunteers will be handing out purple ribbons to pin to people's clothing.Twenty grief counselors from the Colorado Organization for Victim Assistance, a nonprofit that advocates for victims, will be on hand to talk to people who feel traumatized by Hollis's murder, including those who were in the park when it happened. The counselors will be available for one-on-one sessions inside the City Park Pavilion, officials say. Local ministers, community leaders and gang prevention workers will also be on hand.
The current incarnation of City Park Jazz began in 1986, "formed by citizens who wanted to take the park back from the drug dealing and violence that was happening," said board president Chris Zacher. However, the tradition of music in City Park started more than 130 years ago.
"We're not going to let a few thugs take away the liberties that the citizens are entitled to," said Denver police Chief Robert White. Many officers will be in the park Sunday, he said, some to attend the vigil.
A funeral for Hollis will be held the day before, on Saturday, June 30 at 11 a.m. at Denver First Church of the Nazarene, 3800 E. Hampden Avenue. At 2 p.m. on Sunday, Brooks and state Representative Angela Williams are co-hosting a fundraiser at Eden, 3090 Downing Street, to raise money for Hollis's family and twelve-year-old daughter. The fundraiser was organized by Girlz Pushing the Button founder Nita Henry. Donations to the Celena Hollis Memorial Fund will also be accepted at City Park Jazz.
Here are more photos from today's announcement.More from our Follow That Story archive: "Celena Hollis murder: Michael Hancock says gang speculation a distraction."