An abundance of caution?
Authorities later confirmed that a preliminary investigation had found "no firearm, rounds or shell casings or other evidence of shots fired" and that the reports of a shooting were "unfounded".
Sky's US Correspondent Hannah Thomas-Peter, in New York, said: "The NYPD have told me that nobody is in custody and no injuries have been reported."
On Saturday, the Crabtree Valley Mall in Raleigh, North Carolina, was placed in lockdown after reports of a shooting. But a search found no evidence of a gun being fired.