Fans were evacuated from Labatt Memorial Park in the fifth inning of the London Majors home opener on Friday night due to concerns of a possible gas leak at a concession stand.
A number of police and fire department vehicles were called in at around 9:20 p.m., with fans being told over the PA system to leave the premises.
A police news release said there were reports of two people in need of medical attention and that there was of a strong odour of gas in the air.
"They put an announcement on that everybody should slowly and calmly leave the stadium," said Don Miller, who was inside to watch the game.
The emergency evacuation was the result of two people who had collapsed at approximately the same time. Fans told CBC News it happened near a concession stand on the third base side, leading to speculation that it was a gas leak. One fan told CBC News he smelled a noxious odour in the area.
"Upon arrival, two patients were assessed. One patient declined treatment. A second was transported to Victoria hospital, mainly for observation," said Dan Griffiths, operations supervisor with Middlesex London EMS.
Griffiths said a gas leak was not found.
Just after 10 p.m., London Majors spokesperson Matt Hiscox said in an email statement that the game has been "postponed" but didn't have any other details.
By that time, the stadium had been cleared. Officials inside the stadium began raking the field and said the game had been postponed.
Coun. Shawn Lewis was at the game and said he saw at least one person on the ground after the evacuation announcement was made who appeared to have temporarily lost consciousness.
"I would personally express my thanks to Majors fans who responded calmly and left the park in an orderly manner, allowing emergency services to do there job," said Lewis in a text message to CBC News.
By 10:30 p.m. all emergency personnel had left the scene and the park was empty with the exception of a few staff. There is no word yet on if, or when, the Majors home opener will be rescheduled.