Hundreds of heavily armed police in Sydney and Brisbane stormed into homes and businesses before dawn on Thursday and have detained at least 15 people, believed to be plotting violent acts against the public. (Reuters)

In what was called the largest anti-terror operation in Australian history, police have arrested 15 people allegedly linked to the Islamic State, some who plotted a public beheading.

Police said the planned attack was to be “random.” The killers were to behead a victim and then drape the body in the black Islamic State flag, according to the Sydney Morning Herald.

The Associated Press reported 800 officers raided more than a dozen locations in Sydney, Brisbane and Logan.

New South Wales police posted footage of one of the raids.

“The police activity today was about preventing this group at the earliest possible opportunity and ensuring their plans did not come to fruition,” Andrew Colvin, acting Australian Federal Police deputy commissioner, said in a statement.

“Direct exhortations were coming from an Australian who is apparently quite senior in [the Islamic State] to networks of support back in Australia to conduct demonstration killings here in this country,” Australian Prime Minister Tony Abbott said at a press conference, as the BBC reported. “So this is not just suspicion, this is intent and that’s why the police and security agencies decided to act in the way they have.”

One of those arrested, Omar Azari, appeared in court today, police told The Washington Post.

Dan Box of the Australian has been tweeting from court. He reported Azari is accused of conspiring with Mohammad Ali Baryalei, “alleged to have become one of the top recruiters in Australia for Islamic State,” according to the Australian.

 

On Sept. 12, Australia raised its terror alert level to “high” based on alleged threats linked to the Islamic State. This is the first time the alert has been raised to this level since the system was introduced in 2003, as CNN reported. The only higher threat level is “extreme.”

About 60 Australians are thought to be fighting with the Islamic State in Syria. Baryalei, a bouncer, allegedly recruited half of them.

Abbott has spoken out against Australian jihadist Khaled Sharrouf, who allegedly posted photos of him and his son with severed heads on social media.

Raban Alou, 21, told the Sydney Morning Herald that his family’s home was raided at around 4 a.m. on Thursday. He said police arrested his brother, and that a warrant indicated they were looking for links to al-Qaeda and the Islamic State.

“It’s a war on Islam just because we grow our beards,” he said

The Sydney Morning Herald also reported death threats “similar to Islamic State’s” were made on a Christian school in Sydney this week.

Men driving a car holding a flag similar to the Islamic made verbal threats at the Maronite College of the Holy Family from a car outside the school.

“They said they were going to kill Christians,” a nun said.