FERGUSON, Mo. (AP) — Ferguson was a community on edge again Monday, a day after a protest marking the anniversary of Michael Brown’s death was punctuated with gunshots and police critically wounded a black 18-year-old accused of opening fire on officers.

Police, protesters and people who live and work in the St. Louis suburb were bracing for what nightfall might bring following more violence along West Florissant Avenue, the same thoroughfare that was the site of massive protests and rioting after Brown was fatally shot last year in a confrontation with a white Ferguson officer.

“Of course I’m worried,” said Sandy Sansevere, a retired health care worker who volunteers at the retail store operated by the nonprofit group I Love Ferguson, which was formed after Brown’s death to promote the community. “What scares me are the guns.”

The father of the suspect who was shot called the police version of events “a bunch of lies.” He said two girls who were with his son told him he was unarmed and had been drawn into a dispute involving two groups of young people.

St. Louis County Executive Steve Stenger declared a state of emergency, which authorizes county Police Chief Jon Belmar to take control of police emergency management in and around Ferguson.

Protests spilled outside of Ferguson. About 50 protesters were arrested around midday Monday for blocking the entrance to the federal courthouse in downtown St. Louis. Among those arrested was scholar and civil rights activist Cornel West.

That protest, like other commemoration events over the past few days, was largely peaceful and somber. But on Sunday, several hundred people gathered in the street on West Florissant, ignoring an officer on a bullhorn repeatedly warning them to get to the sidewalk or face arrest. Eventually, a few lobbed glass bottles and rocks at officers. One officer was hospitalized with cuts to the face after being hit with a rock. Two others had minor injuries after protesters sprayed them with pepper spray.

As tensions escalated, several gunshots suddenly rang out from the area near a strip of stores, including some that had been looted moments earlier. Belmar believes the shots came from about six different shooters. What prompted the shooting was not clear, but Belmar said two groups had been feuding. The shots sent protesters and reporters running for cover.

The shooters included the suspect, identified by his father as 18-year-old Tyrone Harris Jr., whom police had been watching out of concern that he was armed, Belmar said.

During the gunfire, the suspect crossed the street and apparently spotted plainclothes officers arriving in an unmarked van with distinctive red and blue police lights, Belmar said. The suspect allegedly shot into the windshield of the van.

The four officers in the van fired back, then pursued the suspect on foot. The suspect again fired on the officers when he became trapped in a fenced-in area, the chief said, and all four opened fire.

Harris was in critical condition after surgery early Monday. Prosecutors announced 10 charges against him – five counts of armed criminal action, four counts of first-degree assault on a law enforcement officer and a firearms charge. All 10 are felonies.

All four officers in the van, each wearing protective vests, escaped injury. They were not wearing body cameras, Belmar said.

Tyrone Harris Sr. told The Associated Press his son was a close friend of Michael Brown and was in Ferguson Sunday night to pay respects.

The elder Harris said his son got caught up in a dispute among two groups of young people and was “running for his life” after gunfire broke out.

“My son was running to the police to ask for help, and he was shot,” he said. “It’s all a bunch of lies … They’re making my son look like a criminal.”

Belmar said the suspect who fired on officers had a semi-automatic 9 mm gun that was stolen last year from Cape Girardeau, Missouri.

Belmar drew a distinction between the shooters and the protesters.

“They were criminals,” he said of those involved in gunfire. “They weren’t protesters.”

Gov. Jay Nixon agreed, saying in a statement that such “reprehensible acts must not be allowed to silence the voices of peace and progress.”

Some protest groups said police were too quick to go into riot mode. Others questioned why plainclothes officers were part of the patrol.

“After a year of protest and conversation around police accountability, having plainclothes officers without body cameras and proper identification in the protest setting leaves us with only the officer’s account of the incident, which is clearly problematic,” said Kayla Reed, a field organizer with the Organization of Black Struggle.

Belmar said it is common to use plainclothes officers. In addition, there were more than 100 uniformed officers from the Missouri State Highway Patrol and the Ferguson and St. Louis County police departments.

Some protest leaders worried about how the latest police shooting – especially on a day honoring Michael Brown – could escalate tensions.

“It changes the equation,” said Rebecca Ragland, an Episcopal priest who was part of a group that marched to the federal courthouse in St. Louis. “The way the police will respond now will be much more militaristic. It legitimizes a response from the police that’s a lot more aggressive.”

John Gaskin III, a member of the NAACP national board from St. Louis, was more hopeful.

“I don’t believe there will be looting or rioting,” he said. “That’s not in my vocabulary. We have to have some faith, and that’s what I believe.”