Ruby Rose -- Gunman Arrested in Her Backyard

10:40 AM PT -- Law enforcement sources tell TMZ, Ruby was not the one who called police and it didn't happen at her home. We're told a man was trying to break into her neighbor's house and was arrested.

Ruby Rose got a terrifying taste of L.A. -- she spotted an armed man in her backyard as police swarmed her house ... searching for the man.

Ruby shot video of the panic -- cop cars on the street and helicopters above her house. She narrated the clip, saying ... "Policemen ... looking for a f**king gunman."

She also live tweeted the incident throughout the search ... "This is petrifying. Helicopters, police, dogs ... and a crazy person"

Ruby says the gunman was eventually arrested ... and she deleted all her tweets about the incident.

It's unclear if the suspect was trying to get into her house ... or just running through the neighborhood. Either way ... scary night for the "Orange is the New Black" star.