More than 20 people from around the country faced domestic terrorism charges Monday after dozens of young men in black masks attacked the site of a police training center under construction in a wooded area outside Atlanta that has become the flashpoint of conflict between authorities and left-leaning protesters.

Two of those arrested are from Georgia but the others hail from around the country, police said. One suspect is from France and another is from Canada, according to police, who did not release further details about the suspects.

Atlanta Police Chief Darin Schierbaum said at a midnight news conference that several pieces of construction equipment were set on fire Sunday at the site for the Atlanta Public Safety Training Center in DeKalb County.

Surveillance video released by police show a piece of heavy equipment in flames at the facility under construction that opponents call “Cop City.” It was among multiple pieces of construction equipment destroyed, police said.

Protesters dressed in all black threw large rocks, bricks, Molotov cocktails, and fireworks at police officers Sunday at the construction site, police said.

Other police agencies stepped in to assist city officers, and no officers were injured, Mr. Schierbaum said. Officers used nonlethal enforcement methods to disperse the crowd and detain those involved, he said.

“This was a very violent attack, very violent attack,” Mr. Schierbaum said. “This wasn’t about a public safety training center. This was about anarchy … and we are addressing that quickly.”

Georgia’s governor, Brian Kemp said the people involved “chose destruction and vandalism over legitimate protest, yet again demonstrating the radical intent behind their actions.”

“As I’ve said before, domestic terrorism will NOT be tolerated in this state,” Mr. Kemp said in a statement Monday.

“We will not rest until those who use violence and intimidation for an extremist end are brought to full justice,” he said.

The names of those in custody and the criminal charges against them were not immediately available early Monday, The Atlanta Journal-Constitution reported. But Mr. Schierbaum said many were not from the Atlanta area.

In January, a 26-year-old environmental activist was shot to death by law officers in the forest where the training center is being built.

Demonstrations spread to downtown Atlanta on January 21, when a police cruiser was set ablaze, rocks were thrown and fireworks were launched at a skyscraper that houses the Atlanta Police Foundation. Windows were shattered in that building and others.

The Atlanta City Council approved the $90 million Atlanta Public Safety Training Center in 2021, saying a state-of-the-art campus would replace substandard offerings and boost police morale, which is beset by hiring and retention struggles in the wake of violent protests against racial injustice that roiled the country after George Floyd’s death in 2020.

In addition to classrooms and administrative buildings, the training center would include a shooting range, a driving course to practice chases and a “burn building” for firefighters to work on putting out fires. A mock village featuring a fake home, convenience store and nightclub would also be built for authorities to rehearse raids.

Opponents have said the site will be used to practice “urban warfare.” Self-described “forest defenders” say that building the 85-acre training center would involve cutting down so many trees that it would be environmentally damaging.

More protests are planned in coming days, police said Monday. “With protests planned for the coming days, the Atlanta Police Department, in collaboration with law enforcement partners, have a multi-layered strategy that includes reaction and arrest,” police said in a statement.