The FBI detonated explosives in a Bucks County storage unit while continuing to investigate two local teens charged with terrorism in N.Y.

The FBI conducted controlled detonations Monday night of explosive materials found in a Middletown Township storage facility, police said — part of the ongoing investigation into two Bucks County teens who have been charged with trying to set off homemade bombs outside Gracie Mansion in Manhattan over the weekend in support of ISIS.

Middletown Township police said the FBI “safely disposed of explosive materials that were recovered during the execution of search warrants” in a storage facility on South Flowers Mill Road. An FBI spokesperson said in a statement that the search “revealed explosive residue.”

Authorities did not specify what the materials were, or say whether the items were linked to Emir Balat, 18, of Langhorne, or Ibrahim Kayumi, 19, of Newtown, who were charged earlier Monday in New York with crimes including use of a weapon of mass destruction and attempting to support a foreign terrorist organization.

Still, the development served as the latest update in the high-profile case, which has attracted international attention as questions continue to swirl about who the men are and why they apparently veered from a life in the bucolic Philadelphia suburbs and onto a path that police said nearly ended in violence.

Representatives of the U.S. Attorney’s Office in Manhattan, which is prosecuting the case, did not immediately respond to a request for comment Tuesday, and the men’s attorneys were not immediately available.

The case has attracted widespread attention, in part because it occurred outside the residence of New York City Mayor Zohran Mamdani, who is Muslim, and because it occurred amid chaotic, dueling demonstrations that pitted far-right protesters expressing anti-Islamic views against hundreds of counterprotesters, including Balat and Kayumi.

The interest was only deepened by news that explosive devices had been lobbed during the tumult — and by the unresolved questions about the apparent allegiance of Balat and Kayumi to ISIS, which prosecutors said the men expressed during interviews with police after their arrests.

Neighbors and former classmates were generally tight-lipped Tuesday when asked about Balat and Kayumi. One classmate of Kayumi’s at Council Rock North High School — from which he graduated in 2024 — described him only as “reclusive,” while others declined to talk about him.

In Langhorne, where Balat lives with his family on a street of homes with manicured lawns and American flags, residents who spoke with The Inquirer said they either did not know his family or had exchanged nothing beyond obligatory pleasantries.

One neighbor, who asked not to be identified because of the nature of the alleged crimes, said she met Balat’s mother around 11 years ago, when the family was considering buying their home. But the woman said she did not recognize Balat when his photo was shown across media outlets after the attempted bombing outside Gracie Mansion on Saturday.

“It was scary,” the woman said. “Not super-duper scary, because I knew he was caught. If he were still here, we wouldn’t be here. It really does make you think — you don’t know what’s going on.”

Mehmet Isak, a former president of the Turkish American Muslim Cultural Association, a mosque and community center in Levittown, said that Balat’s father is a regular visitor, but that he did not know or recognize Emir Balat.

Balat’s father “comes to the mosque every once and a while, like everyone else,” Isak told The Inquirer. “But the suspect, we don’t know him at all.”

Isak said Balat’s father runs a construction business and has lived in Bucks County for decades.

Asked for his reaction to Balat’s arrest, Isak said: “If someone has done something wrong, they will pay the price. Our congregation does not support or stand behind wrongdoing.”

An Inquirer review of publicly available records shows few obvious links between Balat and Kayumi, and Balat’s attorney, Mehdi Essmidi, said Monday that he was not even sure the men knew each other before the weekend. It remained unclear Tuesday how they may have ended up at the New York City protest together.

The review also offers few clues about how Balat and Kayumi may have come to apparently support the Islamic State.

But prosecutors said both men were definitive about it while being interviewed by police: Kayumi, they said, admitted watching “ISIS propaganda” on his phone, while Balat, in a separate interview, wrote a note expressing allegiance to ISIS and then told officers he had hoped to carry out an attack more deadly than the 2013 Boston Marathon bombing.

“No, even bigger,” Balat said, according to prosecutors. “[That] was only three deaths.”

Balat and Kayumi both hailed from upwardly mobile immigrant families, records show. Both families appear to have been based in the New York City metro area before settling in Bucks County in the 2000s.

Balat grew up in Langhorne, the son of Turkish parents. His father was granted asylum in 1998 and gained citizenship in 2017, according to court records. His father ran a painting business, according to a 2009 bankruptcy filing, which lists his mother as a homemaker at that time. Balat is a senior at Neshaminy High School.

Kayumi’s parents were naturalized citizens originally from Afghanistan, and his father followed a social media page for the Timur Cultural and Social Association, a Philadelphia-based group that “celebrates the cultural heritage of the Turkic people of Afghanistan.”

In a commencement video of his 2024 graduation, Kayumi can be seen walking up to accept his diploma with little outward emotion.

Council Rock’s superintendent, Andrew J. Sanko, sent a letter to parents this week addressing Kayumi’s arrest. Although Sanko did not name Kayumi — referring to him only as a “former student” — Sanko said there was “no evidence to suggest that [Kayumni] has posed any threat to any Council Rock schools.”

Online biographies list Kayumi’s parents as involved in the management of Popeye’s Chicken franchises. A 2022 franchisee directory lists his father at one location in New Jersey, while tax court records in New York state document a dispute over his investment at a Brooklyn-based outpost of the chain in the 2010s.

As for the incident in New York on Saturday, authorities said the men traveled to the city in a car with a New Jersey license plate that was registered to one of Balat’s family members.

Kayumi’s mother had filed a missing-person report for her son that day, saying she had last seen him around 10:30 a.m.

By that time, police said, he was on his way to the Upper East Side, where far-right provocateur Jake Lang had organized an anti-Muslim protest called “Stop the Islamic Takeover of New York City,” said New York Police Commissioner Jessica Tisch.

More than 100 others then gathered for a counterprotest dubbed “Run the Nazis out of New York City,” Tisch said. As tensions between the groups swelled, Tisch said, someone in Lang’s group sprayed counterprotesters with Mace.

A melee ensued, Tisch said, and a counterprotester later identified as Balat threw a fiery device toward Lang’s group, sending people running for cover.

Balat ran down the block and got a second device from Kayumi, she said. Balat then lit that device but dropped it, she said.

He and Kayumi were taken into custody at the scene, police said, and although neither device thrown by Balat exploded, the FBI later tested them and found one contained TATP, a highly volatile explosive substance used in many terrorist attacks.

A police official speaking alongside Tisch said that the NYPD conducted controlled detonations of both devices, and that they resulted in “a significant explosion” with the possibility of causing “death and destruction.”

The teens then went on to tell police about their ISIS devotion, officials said, including in NYPD cars as they were transported to a precinct to be interviewed, where they elaborated on how they followed the organization. Balat, in a note he wrote on a piece of paper for investigators, concluded by using the phrase “die in your rage,” police said, which they described as a slogan used by ISIS.

Both men remained jailed without bail Tuesday. It was not immediately clear when they would next be due in court.