India, March 9 -- An improvised explosive device (IED) with the potential to cause "serious injury or death" was detonated and hurled during the Jake Lang-led protests near Gracie Mansion on Saturday, according to New York City officials.

The devices were found near the Upper East Side residence earlier in the day, triggering a major security response involving the New York Police Department (NYPD), federal investigators and bomb-squad units. Authorities later detained several individuals in connection with the incident.

Multiple people briefed on the matter told NBC News that the militant group ISIS was referenced, prompting investigators to examine whether the incident could be linked to the militant group.

The two men in custody, Em...