A teenager carrying a replica pistol in Birmingham could have faced "fatal consequences" when he was caught by armed officers, police have said.
Armed officers drew their weapons when the 15-year-old reached for the gun after a chase.
West Midlands Police said they got a 999 call just after 21:30 GMT on Monday reporting a youth carrying a handgun near Moor Street station.
Ch Insp Paul Minor said the teenager had had a "lucky escape".
After the initial emergency call CCTV operators guided armed officers who followed the youth on to a bus travelling along Corporation Street.
As officers closed in the teenager ran from the bus and moments later was "staring down the barrel of a police MP5" after he motioned towards the pistol which was concealed beneath his hoodie, said police.
Ch Insp Minor said the youth was intending to throw the realistic replica pistol on to the ground, but officers had to treat the gesture as a "genuine threat to public safety".
He said: "Especially at night it can be hard to distinguish between genuine and imitation weapons - this lad had a lucky escape and it was only the professionalism and split-second judgement of the officers that drew the situation to a safe conclusion.
"The lad may have thought it was streetwise to carry an imitation handgun around with him, but it could have had fatal consequences."
A 15-year-old from Kingstanding is currently being questioned by detectives on suspicion of carrying a replica firearm with intent to cause fear of violence, police said.