Play was stopped in the closing stages of the first-leg semi-final encounter by referee Paul Tierney after a supporter is believed to have collapsed.
Paramedics attended to the fan in question for a number of minutes before he was taken to hospital.
Peterborough midfielder Danny Swanson stopped play in the 87th minute by picking up the ball and diverting the referee's attention to the incident.
After a small wait Tierney sent the players back into the dressing room while the fan received treatment from on-site medical personnel.
A number of the players appeared to be visibly shaken by the incident and were seen to make their own silent prayers on the pitch.
The players eventually filtered back onto the field after a 10-minute break, playing out the closing stages as the match finished 2-2 amidst a sombre atmosphere.