It was a sold out match between Nam Dinh FC and Hoang Anh Gia Lai, with 25,000 fans filling up the seats at the Thien Truong Stadium.
The crowded and hot atmosphere caused a lack of air on the stands, causing a small boy to faint and have seizures.
Mobile police officer Tran Duc Giang and his colleagues spotted the situation and were quick to respond. They got the boy out of the crowd.
Giang also put his hand in the boy's mouth to prevent him from choking on his tongue or biting his tongue and took him to the ambulance.
The fans at Thien Truong Stadium became quiet and held their breath as they witnessed the incident. Then they cheered loud and long for the two officers.
The boy, of around five years old, became stable at a nearby hospital.
The game ended in a draw with each team scoring twice.
A similar incident had happened in an earlier V. League 2019 match, but involving a player.
On May 5, referee Ngo Duy Lan did the same thing when footballer Nguyen Hung Thien Duc suffered a brain concussion and passed out after a strong collision in the air.
Similar practice have been done by football players in an effort to save their teammates on the field. Famous players like Fernando Torres and Martin Skrtel have received the same intervention from their teammates.
But doctors said the putting something into a person's mouth during their seizures is not necessary. A chin lift or jaw thrust are recommended maneuvers to save someone from choking on their tongue or biting their tongue, they said.
Dr. Truong Huu Khanh, a senior doctor at the Children's Hospital No. 1 in Ho Chi Minh City, said that although Giang's act of letting the boy bite his fingers was nice, it was not right.
"The cops might have not been trained for this situation," he said.