Dr. Mehmet Oz and a quick-thinking plumber raced to help a British tourist who lost her leg when a taxi jumped the curb outside Rockefeller Center Tuesday afternoon.

The 23-year-old tourist was having a hot dog with a friend by a fountain near a midtown corner after 11 a.m. when the cab lost control and ran over the curb. She was pinned against the taxi, which had slammed into the wall surrounding the fountain in front of 1251 Avenue of the Americas. She lost her right leg below the knee, officials said.

Plumber David Justino rushed over to the bloody scene to help, using his belt as a tourniquet until paramedics arrived. Oz, who was in the News Corp. building, heard the commotion and came down to help, according to his spokesman Tim Sullivan.

Oz, who arrived as first responders were stabilizing the woman, made sure the plumber's makeshift tourniquet was in the right place and that the cabdriver was responsive.

"It was really the work of the paramedics and the good Samaritan plumber who dealt with this," Sullivan said.

Food vendors manning their grills nearby offered up their ice to preserve the severed leg.

Omar Sadik, who works at a Halal food cart, said he gave three bags of ice and a container to the cops. "Lots of people brought whatever they could," said another food cart vendor, Fathy Abouel Magd of Astoria.

Moments before jumping the curb, the taxi driver, identified by the Taxi and Limousine Commission as Mohammad F. Himon, 24, collided with a bicyclist on Sixth Avenue as the biker was turning to head west on 49th Street. The bicyclist ended up on the car's hood, according to Magd, who had a clear view of the accident from 50th Street. The bicyclist had minor injuries that were treated on scene.

The bicyclist, whose name could not be confirmed, told CBS/880 radio that the driver sped up before the crash. "He got angry because I told him to stop," the bicyclist said. "So he deliberately accelerated his car."

The tourist, who was staying at the Hotel Pennsylvania, was taken to Bellevue Hospital Center in critical but stable condition. She underwent surgery to get the limb reattached, the NYPD said. The surgery's outcome wasn't available at press time.

Himon was given a summons for being an unauthorized driver of the taxi at the time of the accident. A police spokesman said an investigation into the accident continues.

"I applaud the quick thinking and heroic actions of David and the first responders," Dr. Oz wrote on his show's Facebook page.

Another person was hurt but refused medical attention.