A FOOTBALL hitting an internal sprinkler was the cause of the MCG's emergency warning system being activated at Saturday's clash between Richmond and Geelong. 

As the teams took their places for the start of the third quarter, an alarm went off around the ground that was accompanied by a voiceover that told those in attendance to evacuate. 

Most of the crowd appeared confused by the alarm and directive, and there wasn't a mad rush to leave the ground.

Play started on time as the sound ceased, and an announcement was made to inform patrons it was a false alarm. 

The MCC later explained it was an incident within the Ponsford Stand that activated the system. 

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"After the localised alarm was raised, there is a five-minute delay before the automated stadium emergency warning system is activated," the MCC said. 

"This five-minute delay allows for the fire brigade and MCC staff to determine the issue.

"It was determined that the cause of the alarm was due to a football hitting a sprinkler on level B1 concourse of the Ponsford Stand. 

"There is a manual override that would have prevented the automated evacuation message going through the stadium. 

"By the time it was determined there was no need to evacuate, the five-minute period had lapsed." 

Geelong coach Chris Scott coached the third quarter from the boundary after the alarm caused chaos.

"We got to our box when it was going off, and my concern was that some of the spectators including the coach's box would be evacuated and I said, 'Well I'm going to beat you to it and get to ground level as soon as I could just in case'," Scott said.

"It wasn't like George Costanza pushing everyone out of the way."