Kirstan Conley and Jessica Simeone (The New York Post)

An off-duty 9-1-1 operator helped police capture a pistol-packing teen on a crowded Staten Island city bus by cleverly ­texting a co-worker to report the armed gunman, cops said.

Coryse Hercules, 28, was riding the S40 bus through St. George around 1:15 p.m. Tuesday when Raysean Alston, 18, pulled a gun out of his pants and stuffed it inside his backpack, cops said.

“He’s got a gun,” one female passenger whispered to a man who was with her, police said.

Alston, who has several prior arrests, then told passengers around him to “calm down,” cops said. “It’s not serious. I carry it for protection,” cops quoted Alston as saying.

Hercules, who was off-duty, decided not to risk a confrontation by calling 9-1-1 within earshot of Alston.

Instead, she used her iPhone to discreetly text a fellow 9-1-1 operator. She gave a detailed description of the gunman and his surroundings, cops said.

Her co-worker Stephanie Williams, 24, was home at the time and contacted on-duty colleagues with the location and a description of the suspect’s black Beats headphones, backpack, mask and skull cap, cops said.

Hercules provided updates about the movement of the bus and the movement of the suspect until cops pulled the bus over.

Alston tried to walk away from the backpack but was nabbed by cops, who found a 9mm semi-automatic handgun with the serial number scratched off, police said.

They also found a silver Smith & Wesson revolver loaded with five bullets and one spent shell casing, cops added. That firearm was reported stolen in Delaware.

Alston was charged with weapons possession.

Copyright © 2013 LexisNexis, a division of Reed Elsevier Inc. All Rights Reserved.