The unidentified woman, an Arizona tourist, was walking to the Taste when she collapsed near Balbo and Columbus around 10:30 a.m., Chicago Fire Department officials said. A good samaritan on her bicycle spotted the woman and began administering cardiopulmonary resuscitation.

Shortly after, fire department paramedics Michael Guerin and Elvis Falbo arrived on their bikes in response to a 911 call. The injured woman didn't have a pulse and was not breathing, but the paramedics were able to shock her heart back into a normal rhythm with an automated external defibrillator from one of their bikes.

"As  soon as we shocked her, we got a pulse back," Guerin said. "I've been a paramedic for 15 years, and this is the first time I've defibrillated someone and had them wake up and start talking."

Guerin said the first words she spoke were, "Where am I?"

The woman was taken to a waiting ambulance by a medical cart and then to Northwestern Memorial Hospital, where she is said to be in serious but stable condition, officials said.

The rescue might not have been possible if not for the paramedics' bicycle team, which can weave in and out of crowded spaces like the Taste with life-saving defibrillators and other medical supplies in tow, said Marc Levison, assistant deputy fire commissioner of EMS operations.

"You can't beat them. They're just invaluable," he said of the team, which is also used to patrol busy downtown areas.

Ninety-five percent of people who go into sudden cardiac arrest die within minutes. The odds of surviving are much better if someone can get blood flowing to the heart by quickly performing CPR and using a defibrillator to restore a normal heart rhythm, as was the case Thursday.

Levison said the Fire Department's response time at the Taste is less than two minutes, in part because of the three, two-man bike teams on site.

On average, paramedics respond to 15 to 25 medical emergencies a day at the food fest, he said.

Guerin and Falbo thanked the samaritan, who appeared to have some form of medical training.

"Nothing can be more rewarding than saving somebody's life," said Falbo, a paramedic for 11 years. "I'm just glad we were there."