NEW YORK (CBSNewYork) — Mayor Bill de Blasio said “cowardly threats of violence” against police will not be tolerated after threats were made against two stationhouses in Brooklyn in the wake of the deadly shootings of two officers.

Emergency Services Unit officers were providing additional protection outside the 79th and 81st precincts after investigators confirmed the threats, CBS2’s Janelle Burrell reported.

The Sergeants Benevolent Association tweeted late Tuesday night that the threat came from a confidential informant who said a Baltimore street gang called the Black Guerilla Family planned to storm the precincts for a shootout with police.

The NYPD is not confirming that, but police said Wednesday they were remaining vigilant while investigating the origin of the threats. They didn’t give details on what information they had received or its viability.

“Our city will not be intimidated by those spouting hateful, violent messages,” de Blasio said in a statement. “We will protect the men and women who protect us.”

The FDNY said they also moved Engine 222 Wednesday, which is near the 81st precinct, “out of an abundance of caution.” No other details were provided.

On Tuesday, the 75th and 104th precincts in Queens received telephone bomb threats. Both buildings were swept by the bomb squad and cleared.

Police have already been on high alert since the murders of Officers Rafael Ramos and Wenjian Liu in Brooklyn Saturday.

The gunman, 28-year-old Ismaaiyl Brinsley, had posted online about his plans to attack police prior to the shooting, police said.

“We’ve put in these extra efforts, we’ll probably end up scaling them back, but an awful lot of copycat threats have come in,” Police Commissioner Bill Bratton said Tuesday on “CBS This Morning.”

Officials said they have assessed hundreds of online postings and calls to emergency lines, initiating about 40 threat probes, with about half of those being closed or referred to other agencies.

An 18-year-old was facing charges of making a terroristic threat after authorities said he put up a menacing photo and message online on Saturday hours after the afternoon ambush of Liu and Ramos.

Devon Coley posted a photo on his Facebook page Saturday night of a gunman shooting at a patrol car, symbols showing a gun pointed at an officer’s head and a caption with his local precinct’s number and “next,” according to a court complaint.

His lawyer, Daniel Ades, said Wednesday that the state terroristic-threats law was being misapplied.

“Nobody’s condoning threats against police,” he said, but “even if this is proven, it doesn’t amount to a crime.” He noted that the law requires a “reasonable expectation or fear” that a threat meant to influence government or intimidate the public is about to be carried out.

Prosecutors sought $250,000 bail for Coley, who was already facing unrelated gun possession and other charges, the New York Post reported. Court records show a judge released him without bail on the threats charge.

Police also said a 52-year-old man had been arrested after walking into a Manhattan stationhouse and saying: “If I punch you in the face, how much time will I get?” and refusing to leave.

In addition, two Staten Island residents were arrested in separate incidents on Tuesday. A 16-year-old was arrested on a charge of making a terrorist threat and a 46-year-old man was charged with making a false report.

Bratton has ordered officers to work in pairs as a precaution and auxiliary patrols, which involve officers who do not carry weapons, have been cancelled.

In another tweet Tuesday, the SBA warned officers to “Carry your firearm at all times on duty & off, carry addtional (sic) mags & second weapons. Stay in pairs & be vigilant to people around you.”

SBA President Sgt. Ed Mullins released a statement urging officers to remain cautious.

“…For our fellow officers, we ask that you be aware of your surroundings and wear your vests. If you are on-duty, do not respond alone – back each other up with multiple units. Provide support for one another, stay alert, and continue to defend the residents of our great City…” the statement said in part.

Patrolmen’s Benevolent Association President Patrick Lynch sent out an email to members reminding them they are potential target and asking them to always wear their bullet-proof vests and carry a backup gun, 1010 WINS’ Roger Stern reported.

The PBA also released a statement Wednesday that said in part, “Our number one priority must be to go home safely at the end of each tour. As we have said before, the greatest safety measure we have is each other…Remain alert and aware of your surroundings, both on and off duty.”

The NYPD said it is advising officers to remain vigilant at all times and said all threats are taken seriously and investigated immediately.

Retire NYPD Intelligence officer Sal Lifrieri said threats will only become more common, especially with social media.

“The real problem with all of that free messaging is that the people who are on the fringe, the sort of the person we saw commit those murders, reads the messaging and sees what people are talking about, internalizes it and goes out and acts on it,” Lifrieri said.

In addition to the threats, police have increased security at precincts throughout the city to prevent acts of vandalism, such as loosening lug nuts on the tires of squad cars, and other acts that may endanger the lives of cops, sources told CBS2.

Police said the security measures “will be assessed and police resources will be deployed accordingly.”

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