A group of bikers will hold a Muhammad cartoon-drawing contest outside a Phoenix-area mosque on Friday and they've been told to come armed in case of a "much-anticipated attack."

What could go wrong?

Jon Ritzheimer, a Marine turned anti-Islam activist, has invited thousands of bikers to join him outside the Islamic Community Center of Phoenix for a "peaceful protest" and Muhammad cartoon contest, timed to take place on the Muslim day of communal prayer.

So far, less than 200 people have RSVP'd, but locals and Muslim civil liberties groups are concerned there could be violence.

“I just hope there’s no gun shots or anything going on,” a neighbor, Cristopher Cabrera told ABC 15. Others have denounced the planned event on Twitter and Facebook.

@lsarsour I'm so ashamed of my home state, and I'm wondering what to do. Maybe video tape the "protest", just in case. This is so shameful. — Laura Veg (@VeganGamerGirl) May 28, 2015

Calling the rally "round 2" on the Facebook event page, Ritzheimer says the contest "is in response to the recent attack in Texas where 2 armed terrorist, with ties to ISIS, attempted Jihad."

He encouraged attendees to bring American flags and to "utilize there [sic] second amendment right at this event just in case our first amendment comes under the much anticipated attack." The event is apparently timed to the point at which the mosque "normally host(s) a large prayer."

Image: Facebook

"Round 2" is a reference to the foiled May 3 attack on political activist Pamela Geller's "Muhammad Art Exhibit and Contest" in Garland, Texas, where a cop was shot and two armed assailants killed. ISIS later claimed credit for the attack, though scant evidence has surfaced that shows the militant group in Syria and Iraq had any role in directing it.

The men behind the attack were from the Phoenix area. One of the men studied at the Islamic Center for years.

In October, the mosque issued a statement that said it "joined global, national and local Muslim scholars and leaders in refuting the ideology of the terrorist group ISIS, we are urging ISIS supporters to repent and return to the religion of mercy." Its imam has also denounced ISIS's "misguided philosophy."

Usama Shami, the president of the Islamic Community Center of Phoenix, speaks at the mosque Monday, May 4, 2015, in Phoenix. Image: Ross D. Franklin/Associated Press

The Arizona chapter of the Council on American-Islamic Relations says it has met with federal and local law enforcement authorities to discuss protecting worshipers at the mosque from members of the armed biker gang.

“We thank law enforcement authorities for their proactive effort to ensure the safety of the mosque’s congregation from hate-filled and armed protesters,” said CAIR-AZ Chairman Imraan Siddiqi in a statement sent to Mashable. “The promise of a heavy police presence at the rally of armed biker gang members will help calm fears of harassment and even attacks on worshipers.”

A spokesperson for the Phoenix FBI office confirmed to Mashable that they're providing support to the Phoenix Police Department, which is "well-equipped to handle protests."

Others have condemned the rally.

"This event is yet another reminder of the degree to which 'free speech' demonstrations are often veneers for deep-seated animus," said Georgetown University's The Bridge Initiative, which studies Islamophobia in the public square, in a post on its website. "The point that the Phoenix bikers are making with this event is less about free speech than it is about expressing their hatred of Islam directly to Muslims," it said.

"Imagine going to church or synagogue & finding a protest full of armed people outside? I mean this is sick," wrote Linda Sarsour, a Palestinian-Muslim-American who speaks frequently against Islamaphobia, on Twitter. "What about American Muslims' freedom to pray in peace and without intimidation? What about that?," she added.

Imagine going to church or synagogue & finding a protest full of armed people outside? I mean this is sick. http://t.co/dLqgs1xuEk — Linda Sarsour (@lsarsour) May 28, 2015

In a post defending the event, the ex-Marine claims that "Islam wants to silence us" so, despite the criticism, the rally must go on.