Over 400 illegal immigrants have entered the United States through a human smuggling operation affiliated with ISIS, according to a recent report by NBC News. The Department of Homeland Security (DHS) has identified these individuals due to their connection to the ISIS terrorist network.

Out of the 400 smuggled individuals, 150 have been arrested, but federal officials are still trying to locate and apprehend more than 50 whose whereabouts remain unknown. 

The remaining migrants are reportedly dispersed across 17 states, and law enforcement agencies are working to arrest them. Initially, these migrants were detained by US Border Patrol but were released because there was no information at the time linking them to terrorist groups. 

Officials said that federal law enforcement agencies are “not panicking” about the individuals who have been identified as “subjects of concern,” but are prioritizing them for arrest and deportation out of caution, per NBC News.

Christopher O’Leary, former FBI counterterrorism section chief, commented on the situation, saying, “The fact that the whereabouts were unknown is clearly alarming.”

“I believe the [U.S.] is scrambling to locate these individuals, and using the immigration charges is not uncommon. They are in violation of that law. And if you need to take somebody off the street, that’s a good approach to do it,” O’Leary continued.

This report follows news from earlier this month that eight ISIS suspects were arrested in the US after entering the country illegally through the southern border. In the wake of a surge of terrorist attacks carried out by ISIS, including the deadly shooting in Russia that happened earlier this year, US officials continue to warn that members of the terrorist group could continue to enter the country from Mexico.