armed and dangerous

Possessing a weapon and likely to use it against others. Typically said of criminals, especially fugitives. The most wanted fugitives on this list are all considered armed and dangerous. Police have said that the suspect is armed and dangerous, and they are urging the public to use caution if he is spotted. They said on the news that the carjacker is armed and dangerous.

*armed and dangerous

Cliché [of someone who is suspected of a crime] having a gun or other lethal weapon and not being reluctant to use it. (This is part of a warning to police officers who might try to capture an armed suspect. *Typically: be ~; be regarded as ~; be presumed to be ~.) The murderer is at large, presumed to be armed and dangerous. The suspect has killed once and is armed and dangerous.