The 23-year-old woman was shot in a Kerang farm spotlighting accident about 11.30pm. 

She was transferred from Kerang Hospital to Bendigo Health at 1.30am.

Bendigo Health spokesman Shaun Makepeace said the woman was resuscitated in the emergency ward when she arrived.

"She had life-stabilising surgery in the theatre before being transferred to the Alfred Hospital at 4am," he said.

The woman, who is an American tourist on an extended stay, remains in a critical but stable condition at Melbourne's Alfred Hospital.

Acting Sergeant Roberta Barry said the woman was sitting in a vehicle with two loaded rifles when one went off as another passenger got in.

"The firearm has discharged accidentally and it really is a very unfortunate accident to have occurred," acting Sergeant Barry said. 

Acting Sergeant Barry said it was unlike anything she had seen in the region in the last decade. 

"Years ago these type of incidents occurred frequently but they very rarely occur now," she said. 

"I can't even remember the last time something similar has happened - it'd be the first one for at least the last 10 years."

She said it reinforced the message to be vigilant around firearms.