Luton have confirmed that Tom Lockyer suffered a cardiac arrest after the Hatters captain was stretchered off during Saturday's game at Bournemouth.
The club have described Lockyer as 'responsive' and 'stable' after he was taken to hospital.
"Our medical staff have confirmed that the Hatters captain suffered cardiac arrest on the pitch, but was responsive by the time he was taken off on the stretcher," said Luton.
"Tom was transferred to hospital, where we can reassure supporters that he is stable and currently undergoing further tests with his family at his bedside."
Lockyer collapsed in the 58th minute of the match, which was eventually abandoned.
Luton manager Rob Edwards immediately ran onto the pitch at the Vitality Stadium to usher his players away from Lockyer and allow medical staff and paramedics to administer treatment.
Play was suspended as players moved and officials moved to the side of the pitch before heading back to the changing rooms a few minutes later.
Lockyer was then stretchered off, surrounded by medical staff.
A statement from Luton later gave more details on the incident.
It read: "He received further treatment inside the stadium, for which we once again thank the medical teams from both sides.
"Tom was transferred to hospital, where we can reassure supporters that he is stable and currently undergoing further tests with his family at his bedside.
"We would like to thank everyone for their support, concern and loving messages for Locks."
