Emergency services were called to the ground at around 1.40pm, before the Magpies took on Manchester City, after a woman in her 70s collapsed.
Paramedics delivered CPR and she was taken to the Royal Victoria Infirmary, where her condition is described as critical.
An ambulance service spokeswoman said: “We were called at 13:38 to St James Park following reports that a woman in her 70s had collapsed. We arrived on scene at 13:40, and the crew delivered CPR. The patient was taken to the Royal Victoria Infirmary.”
Our thoughts are obviously with her and her family.