A "Draw Muhammad" contest in front of a Phoenix mosque drew hundreds of people, while police kept opposing protesters separated with barriers.
Demonstrators arrived armed with handguns and rifles visible as worshippers assembled for Friday evening prayers. But the event was more of a protest than art contest, as people crowded in front of the mosque holding signs and yelling chants.
The event's organizer, Jon Ritzheimer, encouraged attendees on Facebook to bring American Flags and "utilize there [sic] second amendment right at this event just incase [sic] our first amendment comes under the much anticipated attack."
An hour into the event, the crowd began to thin on both sides.
"I'm a threat because I'm here with a gun?" Ritzheimer asked a reporter at the rally Friday. "They're the ones with the bad track record."
The rally comes just weeks after two gunmen from Phoenix, Arizona, opened fire at a similar event in Garland, Texas, organized by an anti-Islamic group.
Elton Simpson and Nadir Hamid Soofi opened fire and were killed outside the event May 3, an event that organizer Ritzheimer, said inspired him to hold Friday's contest.
Friday's rally, was held at the Islamic Community Center of Phoenix, which had been attended by the two shooters.
Ritzheimer, a former Marine who has described himself as an atheist, told local news outlets he decided to hold the rally after the shooting in Texas to "expose Islam."
"I'm a Marine, and I'm far from politically correct," he told KPNX-TV. "I'm outspoken and I've just had it."
Ritzheimer encouraged people to arrive armed to the event, and told CNN's Anderson Cooper he and his family had received threats, and compared himself to the Founding Fathers.
The Associated Press reported the Phoenix mosque also received threats earlier this week, and the FBI was looking into the threat.
With protesters, counter-protesters, and the incendiary topic of the "Freedom of Speech Rally Round II" local law enforcement officials said they were working with the FBI to keep the event peaceful.
"There's a lot of different angles, a lot of different emotions," Sgt. Trent Crump of the Phoenix Police Department told CNN Friday. "Our goal out here is the safety of everyone."
Before people began to gather at the mosque, local news outlets showed law enforcement officials setting up cameras on the roof of the building.
"I'm not happy this protest is occurring," Mayor Greg Stanton told CNN, calling the event "purposefully provocative."
"We're going to do everything in our power to ensure that this protest happens peacefully," he said.
Before the rally began, Reborn Assistance Association, an organization that provides transitional housing for homeless man, asked its residents to avoid the area.
Counter-protesters also attended the rally, blocking entrance to the mosque and holding signs of their own.
Police stood between the two groups as the crowd swelled, though video of the scene showed people sometimes shouting across the street and engaging each other as police with helmets stood in between.
Drawing the Prophet Muhammad is considered offensive in the Islam, and there were reports that some protesters were doing other offensive acts such as tearing pages from the Qur'an in front of people attending Friday prayers.
By 6:30 p.m., as more people arrived to the front of the mosque, police set up barriers and stood in formation between the opposing protest groups to keep them apart.
As protesters began to arrive, counter-protesters reportedly formed a line on the mosque's sidewalk, blocking access to the building.
Usama Shami, president of the Islamic Center of Phoenix, told KPNX-TV prayers would be held as scheduled, and he encouraged worshipers not to engage with protesters.
"Everybody has a right to be to be a bigot, Everybody has a right to be racist," he said. "They're not looking for an intellectual conversation. They are looking to stir up controversy."