The Premier League game between Watford and leaders Chelsea was stopped after a supporter suffered a cardiac arrest.
Referee David Coote took both sets of players off the pitch at Vicarage Road in the 12th minute with the score 0-0.
Almost 25 minutes after the game was stopped, the supporter was carried out on a stretcher and taken to hospital.
“Our thoughts are with the fan – who had a cardiac arrest but has now been stabilised – and all those affected,” said Watford.
“Thank you to the medical staff, players and fans for their quick response.”
The incident happened as Watford defender Adam Masina was receiving treatment.
Medical staff from both teams raced across the pitch to deal with the emergency, as both sets of players returned to the dressing rooms.
Players came back on the pitch after the fan was taken to hospital, and after a short warm-up, the game resumed 32 minutes after it was stopped.
Chelsea said: “The thoughts of everyone at Chelsea Football Club are with the fan and all those affected. Our thanks to the medical staff here at Vicarage Road for their quick response.”