Two teenagers were charged on Monday with offenses including terrorism and using a weapon of mass destruction after they allegedly threw improvised explosive devices during an anti-Islam demonstration on Saturday outside the residence of New York mayor Zohran Mamdani.

According to a 10-page criminal complaint filed in federal court in the US southern district of New York, 18-year-old Emir Balat threw the devices at protesters after they were handed to him by Ibrahim Kayumi, 19. It said both declared allegiance to the Islamic State terror group.

The incident took place on Saturday during an anti-Islam protest by rightwing agitators outside Gracie Mansion on Manhattan’s Upper East Side. Mamdani, the city’s first Muslim mayor, and his family were not at home.

Neither device exploded, and both were made safe by the NYPD bomb squad.

The defendants, from Pennsylvania, were expected to be arraigned on Monday afternoon.

The document, signed by federal magistrate judge Gary Stein, lists five charges against each: attempted provision of material support and resources to a designated foreign terrorist organization; use of a weapon of mass destruction; transportation of explosive materials; interstate transportation and receipt of explosives; and unlawful possession of destructive devices.

It said Balat was arrested in possession of a Turkish government ID and a Pennsylvania driver’s license in his name. It gave no details of Kayumi’s nationality, but said he was reported missing by his mother in Pennsylvania earlier on Saturday.

Jessica Tisch, the New York police commissioner, told reporters at an earlier press conference in Manhattan that the devices contained triacetone triperoxide (TATP), a homemade and highly volatile chemical explosive known as “mother of Satan”.

“These were not hoax devices, nor smoke bombs,” Tisch said. “They were improvised explosive devices that could have caused serious injury or death.”

Tisch said she could “confirm that this is being investigated as an act of Isis-inspired terrorism.”

According to an FBI agent with the New York joint terrorism taskforce whose name appears on the criminal complaint, Balut and Kayumi admitted their involvement in Saturday’s attempted bombing.

“At approximately 12.15pm, an individual later identified as Emir Balat ignited and threw an item toward the area where the protesters were gathered,” that agent, Jennifer Gioia, wrote.

“Immediately after throwing device 1, Balat ran to another location down the block and received a second item from an individual later identified as Ibrahim Kayumi. After apparently igniting device 2, Balat dropped [it] near where several NYPD officers were standing, ran away from the officers, and jumped over a barricade. He was tackled and arrested.”

After their arrests, Gioia said, Balat pledged allegiance to IS, and Kayumi said his actions were “partly inspired” by the group. Balat, the document states, wanted his bombing to be “even bigger” than the terrorist attack on the 2013 Boston marathon that killed three and injured hundreds.

Mamdani said the men had “traveled from Pennsylvania and attempted to bring violence to New York City”. The mayor praised two police officers whose “swift and decisive actions” he said led to the suspects’ prompt arrest as well as the devices being removed safely.

“New York City will never tolerate violence, whether from protests or counter-protests,” he said, referring to the Stop the Islamic Takeover of New York City demonstration of about 20 people organized by far-right influencer Jake Lang, and dozens more who turned up to oppose it.

“Many of the counter-protesters met this display of bigotry peacefully with a vision of a city that is welcoming to all, but a few did not.

“Anti-Muslim bigotry is nothing new to me, nor is it anything new for the one million or so Muslim New Yorkers who know this city as our home. While I found this protest appalling, I will not waver in my belief that it should be allowed to happen.”

Six people were arrested at the protest, which the New York Times reported featured several violent skirmishes, the throwing of raw eggs, and at least one of Lang’s supporters pepper-spraying a counter-protester.

Tisch said the NYPD was already on a heightened state of alert for terrorist acts because of the US and Israeli military strikes in Iran that began on 28 February. But Tisch said “we do not have any information that connects this investigation to what’s going on overseas in Iran”.

Tisch added that the investigation was in its preliminary stages. And she said there was nothing so far that suggested the two arrested men had made any threats on social media or announced their intention to travel from Pennsylvania to New York.

She said a third suspected device “consistent with the first two explosive devices” was found in a 2010 Honda tied to the suspects and parked nearby. The device was removed by a robot and tested negative for explosives. She said there was no information about a possible third suspect linked to the arrested men.

Only one of the thrown devices was confirmed to contain TATP, Tisch said, and both were sent to an FBI explosives lab for further testing. The commissioner said the last time an improvised explosive device was used in New York was a 2017 terrorist attack on the Manhattan subway that injured four people.

“We were fortunate that the devices used this weekend did not cause the kind of harm that they were certainly capable of causing,” she said.

“But luck is never a strategy. Devices like these have the potential to cause devastating harm, which is why the NYPD does thorough counter-terrorism investigations and treats every incident of this kind with the highest level of urgency and care, and it is why we remain vigilant.”