Police arrested a 19-year-old over an alleged mass shooting plot targeting an Illinois Hindu temple. A jammed rifle and a colleague's alert may have prevented mass casualties.

A 19-year-old man has been arrested for allegedly plotting a mass shooting at a Hindu place of worship in Illinois, United States. Investigators said his gun jammed when he tried to open fire, prompting him to return home and preventing a possible mass killing.

Police recovered electronic communications and a manifesto attributed to the accused, Alexandros Paporakis, which expressed white supremacist and extremist views and referred to violence against South Asians, particularly people of Indian descent. He has been charged with making a terrorist threat and unlawfully possessing a weapon.

Paporakis, a resident of Palatine village, was arrested on October 11. Investigators believe he may have planned to carry out the attack that day, though authorities have not confirmed or disclosed the intended location.

Palatine Police said detectives examined electronic communications and a document attributed to Paporakis titled “Why I Fought: A.K.A.: (Aurora Shooter's Manifesto)”. It contained “statements expressing white supremacist and extremist ideologies, including references to violence directed toward individuals of South Asian heritage, particularly those of Indian descent”.

“However, the specific intended location has not been confirmed and remains under investigation,” police said on Wednesday.

The investigation began after the Mount Prospect Police Department contacted Palatine Police on October 11 with information about a possible mass shooting. The information came from a person who had received concerning electronic communications from Paporakis.

NBC Chicago reported that Paporakis, who had worked as a cashier at fast-food restaurant Taco Bell, had plotted a “mass shooting of Indian people” at a Hindu temple in Aurora.

According to the report, he drove to the temple last Sunday “decked out for war” on a day when the sprawling place of worship was crowded. He was “one malfunctioning rifle away from becoming a mass shooter”.

Quoting police, the report said Paporakis had arrived “to kill a significant number of Indians”. Investigators said he had a modified AR-style rifle, 300 rounds of ammunition sufficient to fill 10 magazines, body armour, gasoline cans and an assortment of Hakenkreuz, the hooked cross used by the Nazis.

Paporakis allegedly drove from his mother's home in Palatine to the Aurora temple. Authorities said “he tried to open fire but the gun jammed, so he drove home”.

At home, he searched online for instructions on how to clear the jammed gun and called a colleague, telling them of his intention to carry out a mass shooting. The colleague alerted police, and Paporakis was arrested before he could return to the temple.

He was arrested while leaving his residence in a coordinated operation by the Palatine and Mount Prospect police departments.

Investigators said Paporakis “expressed pleasure calling himself a sociopathic white supremacist Neo-Nazi filled with hatred, fantasising about mass murder nearly every day”.

He appeared for a detention hearing on Wednesday at the Cook County Third Municipal District Courthouse in Rolling Meadows. A judge ordered that he remain in custody, and his next court appearance is scheduled for October 30.

The Consulate General of India in Chicago said it appreciated the timely action by law enforcement authorities. It said it was in touch with members of the Indian diaspora and was closely monitoring developments.

The arrest came during celebrations of Hindu festivals, including Navaratri and Durga Puja, and two weeks after the Shree Swaminarayan Vadtal Dham Hindu Mandir in Richmond Heights, Ohio, was vandalised.

In a social media post, the Hindu American Foundation commended law enforcement for its swift action. “We also urge the community to stay vigilant and report any potential threat. Every community deserves to worship without fear,” it said.

The Coalition of Hindus of North America said the “disturbing plot” had emerged as Hindus gathered in large numbers to celebrate Navratri and two weeks after an attack on a temple in Ohio.

“Hindu temples and all houses of worship must be sanctuaries of peace, prayer, and solace — NEVER targets of hate, violence, or terror. We thank law enforcement for their swift action in averting what could have been an unspeakable tragedy,” it said in a social media post.

“We urge elected officials and law enforcement agencies to take the growing threats against Hindu places of worship seriously, strengthen protections, and unequivocally condemn Hinduphobia,” the coalition said.

The group asked temples and community organisations to review their security measures, remain vigilant and promptly report suspicious activity. “The freedom to worship without fear is a fundamental American right. It must be protected,” it said.

Police said they were working with the FBI as the investigation continued, including a review of possible additional charges. Authorities said they had not identified any continuing threat to the public linked to the case.

“The seriousness of this alleged threat cannot be overstated... Protecting our communities and places of worship remains a priority,” Palatine Police Chief William Nord said.

FBI Chicago Special Agent in Charge Ryan Whalen said the agency works closely with local and state law enforcement partners to identify, investigate and dismantle threats of violence driven by radical ideologies.

Paporakis remains detained on charges of making a terrorist threat and unlawfully possessing a weapon as police and the FBI investigate the alleged plot, the intended target and the possibility of additional charges.