Police were called to an early voting centre at Ashfield Town Hall on Liverpool Road at around 1pm today following reports of an assault.
The man, believed to be aged in his 80s, was treated at the scene and has been taken to Royal Prince Alfred Hospital in a serious condition.
Police arrested a 17-year-old boy at the scene.
He has been taken to Burwood Police Station where he is assisting with an investigation.
A crime scene has been established.
The Australian Electoral Commission (AEC) said it is aware of the incident but confirmed the victim was not an election worker.
“The incident occurred outside of our polling place and did not involve any AEC staff,” a spokesperson told 9news.com.au.
“Voting operations are continuing at the pre-poll voting centre in Ashfield.”
Anyone with information is urged to contact police or Crime Stoppers on 1800 333 000.
