Homes Searched in Pennsylvania After Bomb Near N.Y.C. Mayor’s House

Federal authorities on Sunday conducted searches in Pennsylvania as part of an investigation into a homemade bomb that was thrown outside the official residence of Mayor Zohran Mamdani of New York City over the weekend.

Mayor Zohran Mamdani was expected to give an update about the investigation at 9 a.m. local time in New York with this police commissioner, Jessica Tisch. The police have so far arrested two men in the investigation, which is now being led by federal law enforcement, into a demonstration outside Gracie Mansion on Saturday where a counterprotester threw a homemade bomb. The device failed to detonate and no one was injured.

Three people with knowledge of the matter said that the bomb, which failed to detonate but released clouds of smoke, contained shrapnel and was designed to kill or maim. The authorities are examining the motives of two men arrested in connection with the violence. One of them told the authorities that he sympathized with ISIS, according to two of the people.

On Sunday, the F.B.I. carried out a search warrant in Langhorne, Pa., related to an incident on Saturday in New York City, the Middletown Township Police Department said on social media. The F.B.I. also conducted investigatory activities in Newtown Township, Pa., the township’s police department said on Sunday afternoon, without providing more information.

Representative Brian Fitzpatrick, Republican of Pennsylvania, said on social media that the investigations in both locations related to an incident that occurred on Saturday near Mayor Mamdani’s residence, adding that he was in communication with federal and local officials.

A day earlier, the police arrested Emir Balat, 18, of Langhorne, Pa., accusing him of throwing a homemade bomb and another smoking projectile during a counterprotest outside Gracie Mansion that day.

Ibrahim Nikk, 19, of Newton, Pa., who is accused of supplying one of them, was also arrested on Saturday, the police said. No explosions or injuries from the devices were reported and Mr. Mamdani and his wife, Rama Duwaji, were not at Gracie Mansion at the time.

Charges against Mr. Balat and Mr. Nikk had not been determined as of Sunday, the police said.

William K. Rashbaum, Chelsia Rose Marcius and Maria Cramer contributed reporting.