A youth player was taken to hospital after suffering a suspected cardiac arrest during an FA Youth Cup game.
The match between West Bridgford Colts and Boston United at Regatta Way in Nottinghamshire on Thursday night was abandoned after the emergency.
East Midlands Ambulance Service said two ambulances, a fast response car and the air ambulance attended.
The Colts said their player was being treated in hospital but no details of his condition have been released.
The West Bridgford club confirmed the footballer was treated with a defibrillator at the ground before paramedics arrived.
In a statement, the Colts said: "We can confirm that there was a medical incident during our FA Youth Cup game against Boston United.
"Emergency services were called out to our Regatta Way Ground after a player became seriously unwell and they are now undergoing treatment in hospital.
"We would ask that you respect the privacy of those involved at this time and we will comment further when we feel it is appropriate to do so."
East Midlands Ambulance Service said in a statement: "We received a call at 19:50 hours to a medical emergency in West Bridgford, Nottinghamshire.
"We sent two ambulances and a fast response car, and the air ambulance were in attendance.
"We transported one patient to the Queen's Medical Centre, Nottingham, by land ambulance."
Boston United tweeted: "Tonight's FA Youth Cup fixture between West Bridgford and the Pilgrims has been abandoned.
"Our thoughts remain firmly with the player involved."
Boston United photographer Oliver Atkin tweeted: "Only about 5 metres from me... absolutely horrific. Begging for good news.
"Defibrillators are a vital, lifesaving piece of equipment… there should not be one ground in this country without one!"
Football journalist Chris Williams tweeted: "Hug your loved ones, I'm at a FA Youth Cup game this evening where a young player has suffered a SCA [sudden cardiac arrest].
"Four shocks and still unresponsive, three ambulances on site."
Manchester City's Raheem Sterling and Liverpool midfielder Jordan Henderson are among several high-profile players who have urged the government to make defibrillators mandatory at schools and sports clubs.
It comes after Denmark international Christian Eriksen was treated with a defibrillator after suffering a cardiac arrest during a group game at Euro 2020.