An ambulance had to part a packed crowd at this evening's lights switch on.
The vehicle crawled through East Street to get to a person who was being treated by first aiders near the Cross.
The person was lying on the ground but later sat up before being taken into the ambulance by paramedic staff.
A member of St John Ambulance said the person appeared to have collapsed.
He said an additional first aid crew had been organised this year given the size of the crowds expected.
The incident happened at about 6.45pm when the crowds were at their densest following the firework display.
Crowds have now dispersed and the ambulance has left the scene.