Two people are facing charges in connection with threats made to the NYPD less than a week after the fatal shootings of two officers.

Officer Rafael Ramos and Wenjian Liu were ambushed by a gunman last Saturday while they sat in their patrol car.

Emergency Services Unit officers were providing additional protection at two Brooklyn precincts, where they were stationed starting Tuesday. Police said Wednesday they were remaining vigilant while investigating the origin of the threats, which they didn't detail.

Investigators are sifting through the threats to determine which ones are serious and which ones are pranks.