The hosts had gone in front four minutes from the break when Conor Sammon drilled into the bottom left corner.
Kilmarnock had Alexei Eremenko sent off nine minutes into the second half, and he was followed down the tunnel within 11 minutes by visiting players Scott Robertson and Jon Daly, who both received two yellow cards in quick succession.
Sammon elected to square across goal instead of shooting; the ball was then sent back across the box by Eremenko and Sammon lashed a close-range effort into the bottom left corner. Kilmarnock were then reduced to 10 men just 10 minutes after the restart when Eremenko was shown a straight red card for his reaction to a midfield foul by Scott Robertson, the Dundee United player also being booked the incident.
Just before the hour, Robertson received a swift second yellow card for a crunching challenge on Miguel close to his own penalty box; and six minutes later, he was followed to the away dressing room by captain Jon Daly, earning his second booking for the presence of an elbow as he challenged Sammon just 10 minutes after his first yellow card for dissent in the aftermath of the Eremenko incident.
The visitors were rewarded with an equaliser less than 30 seconds from full-time, substitute Kenneth netting with a speculative shot from distance.