PC Jemma Follows has her Taser drawn when the teenager emerges, but he vanishes from sight and she withdraws from the house.
Undeterred, the response officer jumps into a taxi in the hunt for the suspect and others he was with.
PC Follows, 29, then tasers another suspect who was in the house. He was found to have had a knife and cannabis on him.
The night ended in dramatic fashion around two hours later when the gunman, Reece Lones, was arrested after being spotted by firearms officers on Stourbridge High Street in front of Saturday night revellers.
Yesterday (16 January) Lones was jailed for more than two years after admitting possession of an imitation firearm with intent to cause fear of violence.
The drama unfolded on Park Street, Stourbridge, at around 10.15pm on 18 November. Body worn video released for the first time today shows how PC Follows cautiously makes her way through the hallway. Lones appears briefly, raising the gun before turning and fleeing.
PC Follows called for backup and asked members of the public for help, including a taxi driver who took her to where the suspects were last seen.
She then tasered a 17-year-old who had been in the house and was acting aggressively.
He was charged by police and given a conditional caution at court, meaning he will need to attend knife and drugs awareness courses.
Lones, 19, of no fixed address, was jailed for 27 months yesterday at Wolverhampton Crown Court.
DC David Franks, who investigated the case, said: “This was fantastic police work by Pc Follows. She kept her calm throughout, and whether she was dealing with members of the public or suspects, she knew exactly what to do.”
Superintendent Phil Dolby, who oversees the work of firearms officers, said: “This was a fantastic arrest by armed officers. They used the minimum amount of force, while using their training about using strong verbal commands to keep the suspect contained.”
The weapon was found to be a BB gun designed to look like a 9mm semi-automatic pistol.
In interview, Lones admitted that the gun was pointed at PC Follows as he moved, but that he hadn’t deliberately aimed it and had only been messing about with it.
PC Follows, who’s been with the force since 2007, said: “When I saw it, I thought anything could happen. Was I about to be shot?
“It has reminded me not to be complacent. I’ve been to similar jobs since and to a degree, I did think: Is the same thing going to happen again?
“It does stick with me. It’s a reminder not to let your guard down too much because you never know what’s going to happen.”
West Mids Police