Two days after Baltimorean Freddie Gray died from a broken spine suffered in police custody, the FBI sent this alert to local law enforcement, warning cops against “cyber attacks” by “hacktivists.”

Although the alert—sent through the FBI’s Internet Crime Complaint Center—doesn’t mention Gray’s death or Baltimore, the timing of the alert suggests a rising fear of anti-police sentiment off and online:

Law enforcement personnel and public officials may be at an increased risk of cyber attacks. These attacks can be precipitated by someone scanning networks or opening infected emails containing malicious attachments or links. Hacking collectives are effective at leveraging open source, publicly available information identifying officers, their employers, and their families.

It’s been years since “hacktivists”—usually a reference to Anonymous—have wielded much power on the web (the last time Anonymous tried to exact revenge against the police, it fingered the wrong officer). Nonetheless, the FBI suggests local cops and “public officials” pay extra attention to their social media activity (“the act of compiling and posting an individual’s personal information without permission is known as doxing”), and do what they can to conceal the fact that they’re actually cops:

For example, posting images wearing uniforms displaying name tags or listing their police department on social media sites can increase an officer’s risk of being targeted or attacked.

[...] Turn on all privacy settings on social media sites and refrain from posting pictures showing your affiliation to law enforcement.

The alert also instructs police to “limit your personal postings on media sites and carefully consider comments,” which is pretty good advice for literally everyone alive.