NEW YORK (CBSNewYork) – The NYPD is investigating what it’s calling a new “credible threat” to target officers in the Bronx, just four days after a violent weekend when police were targeted by multiple shootings including an attack inside the 41st Precinct.

One of the police unions posted to social media a warning about possible attacks meant to be shared with officers on duty and urging them to “remain vigilant and stay alert.” The NYPD confirmed to CBS2 they called the threat credible.

The Sergeants Benevolent Association shared a photo allegedly showing the internal memo about the 41st Precinct, the same place a gunman attacked on Sunday morning and left one lieutenant wounded in the arm.

WARNING – MUST READ

NYPD COPS ASSASSINATION THREAT- the attached notice has been distributed throughout NYPD Commands. REMAIN ALERT – respond with back up on all 9/11 calls. pic.twitter.com/1EyaXMB0Ep — SBA (@SBANYPD) February 13, 2020

The depicted message states: “INVESTIGATIVE UNITS HAVE RECEIVED A CREDIBLE THREAT OF AN INDIVIDUAL THAT MAY ATTEMPT TO SHOOT A NYPD MOS, IN PARTICULAR, A 41 PCT MOS. ALL MOS ARE BEING ADVISED TO BE VIGILANT AND ALERT. STATIONHOUSE SECURITY MUST BE POSTED ON ALL TOURS. PLEASE ADVISE ALL MOS AND CONTINUE TO READ THIS MESSAGE AT ROLL CALLS UNTIL FURTHER NOTICE.”

MOS, for “member of the service,” refers to officers on the police force. The NYPD is adding security to all police station houses across the city and urging police officers to stay alert.

There is no specific group or person associated with the threat at this time.

Two police officers were shot during a 12-hour span Saturday night into Sunday morning, allegedly by the same gunman.

The weekend suspect, identified as Robert Williams, 45, of the Bronx, initially shot at two officers, wounding one, as they sat in their marked police van in the Bronx, sources said, and later walked into the 41st Precinct, located at 1035 Longwood Avenue, and opened fire, wounding another officer.

After the street ambush on Saturday night, NYPD Commissioner Dermot Shea called the shooting “an assassination attempt at two New York City police officers.”