Ferguson, Missouri (CNN) Crowds scatter and duck for cover around him. But a man in a white T-shirt sprints forward, waving what appears to be a gun in his hand.

Investigators say that image, captured in a surveillance video released by the St. Louis County Police on Tuesday , shows the chaotic scene that erupted in Ferguson, Missouri, as a shooting broke out early Monday during protests marking the anniversary of Michael Brown's death. The man holding a handgun, they say, is 18-year-old Tyrone Harris.

Police have said they later shot the teen after he unleashed a "remarkable amount of gunfire" at officers, a characterization his family disputes.

"From what I heard, he was there with some friends and they had a confrontation. They start shooting at the friends, and he just happened to be at the wrong place at the wrong time," Harris' father, Tyrone Harris Sr., told CNN affiliate KMOV

His aunt, Karen Harris, said the teen attended the protests because he was friends with Brown. Recounting what other family members who were with him described, she said her nephew wasn't carrying a gun and never fired at police. He was "running for his life" just like everyone else, she said, when gunshots rang out.

But police say Harris was firing gunshots himself, an account another person who said he was at the scene of the shooting corroborated.

"Tyrone was right next to me. He was shooting back at them and all that. ... And police shot back at him," 18-year-old Seth Norfleet told CNN.

Authorities have said Harris is hospitalized in critical condition. Prosecutors have charged him with four counts of first-degree assault on law enforcement, five counts of armed criminal action and one count of discharging a firearm at a motor vehicle.

City on edge

The shooting early Monday left the St. Louis suburb on edge as protesters planned more events.

Photos: Ferguson protests mark a year of outrage Photos: Ferguson protests mark a year of outrage Members of a group calling themselves the "Oath Keepers" appear in Ferguson carrying large guns on Monday, August 10, one day after a police confrontation led to a protester being shot. Sunday, August 9, marked the one-year anniversary of the death of Michael Brown. Hide Caption 1 of 15 Photos: Ferguson protests mark a year of outrage Demonstrators protest in Ferguson on August 10. Hide Caption 2 of 15 Photos: Ferguson protests mark a year of outrage A demonstrator is arrested in Ferguson on August 10. Hide Caption 3 of 15 Photos: Ferguson protests mark a year of outrage Protesters march to the Federal Courthouse on August 10 in St. Louis. Hide Caption 4 of 15 Photos: Ferguson protests mark a year of outrage Cornel West, center, joins other protesters sitting on the steps of the Thomas F. Eagleton Federal Courthouse as members of the Federal Protective Service stand watch August 10 in St. Louis. Protesters have been arrested after blocking the entrance to the courthouse while calling for more aggressive U.S. government response to what they call racist law enforcement practices. Hide Caption 5 of 15 Photos: Ferguson protests mark a year of outrage A man with gunshot wounds lies face down in a parking lot after a shootout with police in Ferguson on Sunday, August 9. Demonstrations started peacefully, but gunfire erupted Sunday night. Police say the man fired at them. Hide Caption 6 of 15 Photos: Ferguson protests mark a year of outrage Police take cover after gunfire in Ferguson on August 9. Hide Caption 7 of 15 Photos: Ferguson protests mark a year of outrage Demonstrators march along West Florissant Avenue in Ferguson on August 9. West Florissant is not far from Canfield Drive, where Brown was shot a year ago. Hide Caption 8 of 15 Photos: Ferguson protests mark a year of outrage A protester yells in front of a line of police in Ferguson on August 9. Hide Caption 9 of 15 Photos: Ferguson protests mark a year of outrage Protesters march in the rain in Ferguson on August 9. Hide Caption 10 of 15 Photos: Ferguson protests mark a year of outrage Demonstrators stage a "die-in" along West Florissant Avenue in Ferguson on August 9. Hide Caption 11 of 15 Photos: Ferguson protests mark a year of outrage Police face off with demonstrators in Ferguson on August 9. Hide Caption 12 of 15 Photos: Ferguson protests mark a year of outrage People attend a memorial service outside Canfield Apartments in Ferguson on August 9. Several hundred demonstrators stood in silence at the spot where Brown was shot and killed. Hide Caption 13 of 15 Photos: Ferguson protests mark a year of outrage Brown supporters wear T-shirts with the late teen's picture and the message "Chosen 4 Change" on August 9 as they take part in the remembrance ceremony in Ferguson. Hide Caption 14 of 15 Photos: Ferguson protests mark a year of outrage People walk past a plaque honoring Brown following the memorial service in Ferguson on August 9. Hide Caption 15 of 15

Several peaceful demonstrations unfolded in the area Monday, but violence surged once again at a protest in Ferguson on Monday night as some protesters threw rocks and bottles at police.

The St. Louis County police said frozen water bottles were thrown at officers, prompting them to order the crowd to disperse or face arrest.

"Safety, our top priority, is now compromised. This is no longer a peaceful protest. Participants are now unlawfully assembled," the department tweeted . About 23 arrests were made late Monday and early Tuesday, police said.

Police Chief Jon Belmar tried to calm tensions by speaking with some demonstrators, who then moved from the street to the sidewalks.

However, others seethed as word spread that police had arrested a 12-year-old girl. Police contended she was 18, citing her ID.

.@pritchett_dan The woman pictured is not 12, but 18 years old according to her ID. — St. Louis County PD (@stlcountypd) August 11, 2015

More controversy arose as well over a pair of arrests made last year in the wake of protests over Michael Brown's shooting death: those of The Washington Post's Wesley Lowery and The Huffington's Post Ryan Reilly, who were briefly detained after being told they were trespassing as they worked in a McDonald's along the protest route.

St. Louis County on Monday, 363 days after their arrests and two days shy of the statute of limitations, charged the reporters with trespassing and interfering with a police officer.

Both news outlets cast the arrests as gross First Amendment violations at the time, and they maintained that theme in Tuesday's responses. Marty Baron, executive editor of The Washington Post, called the charges "outrageous," while HuffPo's Washington bureau chief Ryan Grim said it was police who committed crimes by assaulting reporters during "violent arrests." The National Association of Black Journalists called the charges "a direct assault on the free exercise of the First Amendment."

Video posted on social media showed Reilly having another run-in with police early Tuesday. In it, Reilly and an officer are seen tussling -- Reilly tweeted that the officer "tried to grab me and snatched my press badge" -- before Reilly pulls away, putting his hands behind his back and saying, "I'm media. I'm media. I'm media."

Reilly was covering demonstrators who took to the streets in spite of a heavy police presence, scurried away, regrouped and returned.

Among the crowd were a handful of heavily armed members of an organization called the Oath Keepers . A man out on patrol described the group as constitutionalists who were hired to protect reporters for InfoWars.com , a website run by radio host Alex Jones, who has questioned everything from the moon landing to 9/11.

State of emergency

Earlier, a top St. Louis County official declared a state of emergency, saying violence had marred demonstrations marking the one-year anniversary of Brown's death

"The recent acts of violence will not be tolerated in a community that has worked so tirelessly over the last year to rebuild and become stronger," St. Louis County Executive Steve Stenger said in a statement.

The executive order put Belmar in charge of police operations in Ferguson and the surrounding areas.

Ferguson Mayor James Knowles and the City Council issued a statement saying they were disappointed in the behavior on display, calling it "counterproductive" and vowing it wouldn't be tolerated. They also applauded law enforcement officers, who they said "exemplified respect, community engagement and professionalism under extremely difficult circumstances."