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Federal agents on Monday served search warrants in New Jersey and Pennsylvania as investigators probe a possible act of terrorism tied to explosive devices thrown during a protest in New York City.

A New York Police Department source told Fox News that devices hurled into the crowd were packed with nuts, bolts and screws, and contained a chemical substance inside a taped canister fitted with a fuse.

Emir Balat and Ibrahim Kayumi remained in custody as federal teams searched their homes in Bucks County, Pennsylvania, according to federal sources.

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Investigators also executed a warrant at a related address in New Jersey.

This is a breaking news story; check back for updates.

Ashley Carnahan is a writer at Fox News Digital.

The hottest stories ripped from the headlines, from crime to courts, legal and scandal.

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