The NYPD quickly sent out Critical Response Vehicles and heavily armed Hercules team cops to key buildings in the city connected to Canada and its government after news of the shooting in Ottawa.
Deployment of the CRVs and the heavily armed cops was a precaution in direct response to the situation in Canada, the NYPD said. The locations weren't identified, but apparently include consular and UN mission offices, banks and business offices.
A high-ranked city law enforcement official, who asked not to be identified, said extra security precautions have also been taken with buildings associated with Australia and the United Kingdom because those countries, in addition to Canada, have been involved in the U.S.-led military efforts against the Islamic State.
NYPD intelligence officials are also trying to assess whether the Canadian gunman was a "lone wolf" who may have been incited by Internet propaganda or acting on orders from a terrorism "mother ship," the official said.
"It is important to see if he is reacting to propaganda or [orders of] a network," the official stressed.
The military increased security at the Tomb of the Unknowns at Arlington National Cemetery, though the FBI and the Homeland Security Department said there was no specific threat. The U.S. Embassy in Ottawa was placed on lockdown as a precaution.