CLEVELAND -- A political group whose members were arrested Wednesday after burning an American flag at the gates of the Republican National Convention says law enforcement officers are lying to justify an assault on their constitutional rights.

Supporters of the Revolutionary Communist Party say there's no photographic or physical evidence to support the claim by police that they had to intervene because activist Gregory "Joey" Johnson set himself and others on fire.

@CLEpolice/Twitter

Activists who were not arrested say they will document that detainees' clothing was not damaged by flames when they are released from jail, where they remained early Thursday.

The claim that activists caught fire was widely reported Wednesday after the Cleveland Police Department said it happened, and police chief Calvin Williams on Thursday morning said that it was the reason for the intervention that led to 18 arrests.

"The lieutenant that was on the scene with the bike officers and the foot officers actually responded to the person on fire and he had a fire extinguisher," Williams said at a press conference. "He was telling, 'Hey buddy, you're on fire' and he's trying to put the guy out and [they're] trying to push the lieutenant away, and they basically struck the lieutenant and that's when our officers intervened and said, 'Wait a minute'."

Photos from the scene show the lieutenant spraying a liquid directly at the flaming flag, but about two hours after chaos broke loose, the police department tweeted: "Protestor lit flag on fire, then lit himself on fire, catching others on fire."

Some images from the protest do show the flaming flag getting very close to activists, particularly after officers attempted to extinguish the flames. But others could support activist claims.

Williams declined to say if officers could offer any evidence to support their claim activists were on fire. "That will be decided in court," he said.

Gregory 'Joey' Johnson is grabbed by a policeman as the flag he was burning gets close to fellow activists. An officer who later held the half-burned flag can be seen yanking it. The Associated Press

Moments before the police chief spoke, supporters of the communist group that spearheaded the protest with Johnson said police were spreading a "self-serving lie" to justify quashing First Amendment-protected speech.

"It has been reported widely and illegitimately in the media with no fact checking that he was on fire," said Sunsara Taylor, acting as a spokeswoman for the group, who said it was galling police would continue to make the claim after the smoke cleared. "He was never on fire…. No one had been singed."

Is anyone on fire? Photos depicting a chaotic scene do not clearly confirm police claims. (Spencer Platt/Getty Images)

Details of charges facing the 18 activists were released by the city Thursday morning. Two people face felony charges for allegedly assaulting an officer. Almost all are charged with misdemeanors for failure to disperse, 10 are charged with aggravated disorderly conduct, five with resisting arrest and one woman with aggravated arson.

Johnson, the defendant in Texas v. Johnson, the first of two Supreme Court cases knocking down anti-flag desecration laws, was charged only with disorderly conduct. Ironically, Johnson helped establish the constitutional right to burn U.S. flags after being arrested for flag-burning at the 1984 Republican convention in Dallas.

Though the ruling in Texas v. Johnson invalidated state laws against flag desecration, a Reuters photo of one woman being loaded into a police van shows two charges on a police placard, including "desecration of flag." That charge was not included on the city's list of protest charges given to reporters on Thursday.

Photo: Julie Leroy is arrested after attempting to light a second flag on fire:



Taylor said activists believe other untruths are being spread about the arrests. She says protesters did not hear any order to disperse before being arrested for failing to do so, and that the two people charged with assaulting officers were in fact peaceful victims of assault. If anyone created a fire safety threat, it was charging officers who seized the flag, she said.

And Taylor also objected to characterizations that the event was an "attempted" flag burning.

"That imperialist rag was in flames!" she said.

Picturing the RNC View All 58 Images

The National Lawyers Guild had about 10 legal observers in crowd when arrests happened, says Kris Hermes, a spokesman for the group's Ohio chapter, which has been in contact with arrested protesters. He says none of the observers saw a protester on fire, but that one did hear an officer say an order to disperse had been given, though they did not hear the actual order.

Williams said an officer made the dispersal order using a megaphone, and that he personally repeated it to activists face-to-face at least three times. Loud chants of "slavery, genocide and war -- America was never great!" made it difficult for people outside a police cordon to hear any instructions provided to the group.

The arrests came after days of lightly attended protests that surprised organizers. Before the incident, Cleveland police took pains to avoid arresting demonstrators, allowing them to illegally march down major roadways without seeking to immobilize or detain them.

Even if activist assertions that nobody was burned or given audible orders to disperse can be proven, there may be a wrinkle to their claims police were entirely in the wrong, as claims they had effectively set up a safety perimeter are dubious.

UCLA law professor Eugene Volokh, a prominent First Amendment scholar, told U.S. News on Wednesday that specific facts must be established before declaring the arrests illegal.

"Fire is not something to sneer at -- it can risk setting something on fire, lighting people's clothing on fire," he said, and could impermissibly obstruct law enforcement needing to address emergencies.

"I do caution people against assuming because flag burning is constitutional you can burn a flag wherever you want," he said. "Restricting speech because of its non-communicative impact is allowed."

Fine points of First Amendment law are likely to be analyzed during possible future trials or civil litigation, though supporters of the communist group say they are less interested in collected a possible legal award than advocating against mainstream politics.