The incident took place at a morning press conference in Brooklyn with City Council member Diana Reyna when Reyna's 18-year-old intern collapsed to the ground.
Political reporter Dave Evans was on the scene covering the event and said after an immediate call to 911 was made, it was about 30 minutes before the ambulance showed up.
At one point Quinn, who is running for Mayor called Police Commissioner Ray Kelly to try and speed up the process.
The intern was taken to the Woodhull Hospital and is listed in stable condition.
It was not immediately known what caused her to faint, although crews believe the heat contributed to it.
Quinn released the following statement:
"Today, while holding a press conference with Councilwoman Diana Reyna in Williamsburg, a young woman interning for Councilwoman Reyna passed out from what appears to be heat stroke. Thankfully, a member of my NYPD security detail present at the event, who is a trained EMT, provided immediate first aid and ensured that the young woman was conscious, provided with oxygen and was hydrated. My staff immediately called 911 to request an ambulance. It took more than 30 minutes before an ambulance finally arrived. After waiting for close to a half hour, I then called Commissioner Kelly seeking assistance and my city council staff called Hatzolah EMS. Shortly thereafter a Hatzolah ambulance arrived and took the young woman to Woodhull Medical Center."
Quinn called the delay inexcusable. She plans to get to the bottom of it.
The city's new emergency response system has been under fire lately after a series of glitches that caused delays.