Leyton Orient's League One home game against Lincoln City was abandoned after 84 minutes on Tuesday due to a medical emergency in the stands.
A Leyton Orient supporter ran onto the pitch to alert the referee to the medical emergency, before several fans sat on the field to prevent the game from continuing.
Medical staff administered CPR by the side of the pitch before play was halted, British media reported.
The match was called off an hour after play was halted with Leyton Orient leading 1-0.
"The thoughts of everyone at Leyton Orient Football Club are with the individual involved and their loved ones at this distressing time," Leyton Orient said in a statement.
"The club would like to thank all supporters in attendance at Brisbane Road this evening for the understanding and compassion shown during a very difficult situation."
The English Football League (EFL) said a decision on whether the match would be rescheduled would be taken after consultation with both clubs.
