Members of the right-wing group Patriot Prayer stationed themselves on a downtown Portland rooftop with a cache of guns prior to a summer protest, city officials announced for the first time Monday – the same day Mayor Ted Wheeler learned about it, his aides said.

That shocking revelation came Monday as Portland officials scrambled to find a way to end the repeated violent clashes between dueling political factions downtown.

Prior to the start of a scheduled Aug. 4 demonstration, "the Portland Police Bureau discovered individuals who positioned themselves on a rooftop parking structure in downtown Portland with a cache of firearms," Wheeler said during a City Hall press conference. Berk Nelson, a senior mayoral aide, later said the weapons included "long guns."

The people on the rooftop were members of Patriot Prayer, said Assistant Chief Ryan Lee, who appeared at the press conference with Wheeler and other police officials. Police officers seized the weapons found on the rooftop that day, but they were later given back. No arrests were made because the protesters had not broken any laws and all had licenses to carry concealed weapons, Lee said. Neither Lee nor Wheeler named the people who guns were seized from.

Asked why the public was not told of the incident sooner, Chief Danielle Outlaw said, "Hindsight is always perfect." Outlaw said the Police Bureau warns the public that protesters may be armed. Both right- and left-wing demonstrators have come to Portland protests armed, she said.

"We push out information as it becomes available to us. We do the best that we can," the chief said.

Patriot Prayer's leader, Joey Gibson, said Wheeler's statement Monday is the first he heard of the armed rooftop incident. Gibson said he spoke to a Portland police officer following the mayor's announcement, who relayed to him that Patriot Prayer members were readying for the protest at the parking garage and peacefully carrying their guns. Gibson said he does not know who among his group was stopped.

"It sounds like they completely exaggerated it," Gibson said of officials' statements Monday. He said officials made it seem as if there was "some sniper pointing his gun down at people." Gibson said he believes arrests surely would have been made if the incident was as serious as police made it seem.

Saturday, Patriot Prayer held a protests in downtown Portland that was called with one day's notice. As happened with the August 4 protest, it drew left-wing counter-demonstrators, including masked antifascist activists, or antifa, and clashes between the rival political factions ended with police violence.

Violent scenes from Saturday's protest circulated nationally, raising questions about why Portland police and political leaders are allowing the violent dueling clashes to continue month in and month out.

Wheeler learned about the rooftop weapons cache Monday while reviewing an ordinance drafted for him that is intended to end that pattern, said spokeswoman Sophia June. The ordinance would restrict the time and place protesters may demonstrate in Portland if they have clashed violently before.

Wheeler's chief of staff, Michael Cox, said the mayor is briefed by police officials after major events, including large protests. The mayor, who is also the city police commissioner, apparently did not learn of the rooftop incident at the briefing following it. Those briefings "might not include every piece of information," Cox said.

– Gordon R. Friedman

GFriedman@Oregonian.com.