Dakkari McAnuff sent the tweet with a picture of a rifle pointing out a window toward the street.
Police immediately tracked McAnuff down through the twitter link and arrested him on suspicion of making criminal threats.
LAist reports McAnuff followed up the original message with another that showed a man lying on the street near an emergency vehicle.
That photo was captioned, "Man down. Mission completed."
The Los Angeles Times reports the rifle turned out to be an Airsoft, and they don't think he really shot anyone, but that won't stop him from doing some jail time.
According to KTLA, McAnuff's twitter account is down but there are several cached versions of the messages so cops have the evidence needed.
McAnuff’s is still in jail. Bail has been set at $50,000.