Authorities said explosives were found in a Pennsylvania storage unit after two men were charged in connection with throwing a homemade bomb into a protest outside the New York mayor's residence on Tuesday.

According to law enforcement officials and a criminal complaint, Emir Balat, 18, and Ibrahim Kayumi, 19, told investigators they were inspired by the Islamic State group after they were arrested near Gracie Mansion in Manhattan on Saturday.

Much about their motives, the scale of their plans and how they knew each other remains unclear. Explosive devices recovered from the scene are undergoing testing.

The FBI said Monday it had conducted multiple searches in connection with the investigation. Middletown Township police in Pennsylvania said Tuesday that the FBI detonated explosives it found at a Public Storage facility in Langhorne, near where Balat's family lives, in a controlled manner. Kayumi is from Newtown, about 4 miles (6.5 kilometers) north of Langhorne.

"Residents may have heard several loud explosions throughout the night," police said in a Facebook post. "While the noise may have been startling to some residents, there was never any danger to the public."

Balat's lawyer described him as a confused teenager who didn't know what he was doing.

Prosecutors, police and FBI officials said Balat and Kayumi drove into New York City on Saturday and joined a crowd of counter-protesters at a small anti-Muslim rally organized by Christian nationalist Jake Lang.

Balat was captured on video by reporters throwing a device with a lit fuse, from which investigators later recovered the explosive TATP. The object, which also contained nuts and bolts, fizzled out on its own without injuring anyone.

Balat then tried to throw a second object near police officers and flee but was subdued and arrested, according to the court complaint.

Balat and Kayumi are being held without bail after appearing in court Monday, facing charges including attempting to provide material support to a foreign terrorist organization and using weapons of mass destruction. They did not need to enter pleas.

Outside the courthouse, Balat's lawyer, Mehdi Essmidi, said his client, a high school senior, "was having complicated things going on in his personal life."

"I believe he is 18 years old and has absolutely no idea what he was doing," Essmidi said, adding that Balat and Kayumi had not known each other for long.

New York City Police Commissioner Jessica Tisch said Monday there was no evidence linking the attack to an internal struggle in Iran.

After Balat was arrested, officers asked him if he had planned something similar to the 2013 Boston Marathon bombing, which killed three people.

"No, I was aiming for bigger than that," Balat replied, according to the criminal complaint.

They face multiple charges including illegal possession and use of weapons of mass destruction, carrying explosives, and attempting to support a designated foreign terrorist organization, according to the complaint.

By NNP=Hong Seong-gu, Chief Reporter / Special Correspondent NNP info@newsandpost.com