A man reportedly walking around the central city yesterday holding a toy pistol was "heavily intoxicated", police say.
Sergeant Andy Reid was parked on the side of the road about 10am when a member of the public approached him to say they'd seen the 19-year-old carrying a firearm.
The person didn't know if it was a real gun or not, Mr Reid said.
While Mr Reid was looking for the man, police received two or three more calls from members of the public who had seen him.
Mr Reid found the man on Dublin St; he said he had been wandering up Victoria Ave pointing the gun at passers-by.
"He did have a firearm in his hand at the time. Police challenged him with a Taser and firearm of our own."
Nobody was hurt during the arrest, and the firearm turned out to be a toy gun, Mr Reid said.
Mr Reid said the man was "heavily intoxicated". He was assessed by Community Mental Health and will go into their care for several days.
A decision on charges has not yet been made.