A fire that destroyed eight Atlanta Police Department motorcycles was among several acts of vandalism in recent days by a group of "anarchists" aimed at stopping construction of a new public safety training center, Atlanta Police Chief Darin Schierbaum said Wednesday.

Schierbaum spoke at a news conference with Atlanta Mayor Andre Dickens and Bureau of Alcohol, Tobacco, Firearms and Explosives Special Agent In Charge Ben Gibbons. The bureau, along with the FBI, is helping investigate the vandalism.

Homemade "incendiary devices" caused a fire early Saturday at Atlanta police's current training center that destroyed the motorcycles, Dickens said. An hour earlier, vandals had smashed the windows of police vehicles at another location. Authorities believe those involved intended to set those vehicles on fire as well but were spotted by a bystander.

"Collectively, these have been some of the most significant attacks on public safety in our city and in our nation over the past year," Dickens said.

Since the weekend, members of the same group have also tried to intimidate contractors connected to the training center project by flattening tires, vandalizing a home, spraying graffiti and setting fire to construction equipment, Schierbaum said.

Schierbaum cited web postings taking responsibility for some of the vandalism as evidence they were connected and said investigators believe the same individuals carried out each act.

"These acts are of a small determined group that does not represent a wider population," he said.

Dickens and others say the planned $90 million training center would replace inadequate training facilities and help address difficulties in hiring and retaining police officers that worsened after nationwide protests against police brutality and racial injustice three years ago.

Opponents say they worry it will lead to greater militarization of the police and that its construction will exacerbate environmental damage in a poor, majority-Black area. They are hoping to force a referendum on building the project. The "Stop Cop City" effort, which has been joined by activists from around the country, has gone on for more than two years.

Dickens said he and police support peaceful protests against the center, but will not tolerate threats or violence.

More than 40 people have been charged with domestic terrorism in connection with protests at the site, where authorities fatally shot an environmental activist in January while clearing a camp site. City officials say officers fired in self-defense after the protester shot a trooper.

The Georgia Bureau of Investigation is investigating the shooting.