St. Petersburg police spokesman Mike Puetz said the agency got a call late Thursday from a concerned citizen who saw people on the roof of a parking garage at 100 Second Ave. S.
“That unto itself is odd,” Puetz said.
The caller also claimed to have seen the people playing with a gun.
Officers found two men and a female teen runaway hanging out.
They also found several items indicating the people were protesters, including antigovernment T-shirts and a backpack stuffed with a large machete, a pocketknife, tin snips and a pry tool, Puetz said.
The backpack belonged to Trevor Swanson, 19, of St. Petersburg, who is prohibited from having weapons because of a domestic violence injunction.
Police said the other man on the roof, Kyle Shaw, 21, had a BB gun in his waistband.
Authorities also found bandanas, black gloves and a putty that Swanson admitted was for securing a mask, police said.