The Sydney girl had wanted her schoolmates to attend, and the post — which included her address — said they could bring friends if they let her know, Sydney’s Daily Telegraph newspaper reported.
“(It’s an) open house party as long as it doesn’t get out of hand,” she wrote, adding that she had not had time to invite everyone individually.
But within 24 hours more than 20,000 people had replied to the public event to say they were attending and by Tuesday almost 200,000 potential partygoers had reportedly accepted the invitation.
The girl’s father, who asked not to be named, said his daughter had invited “a few friends” over Facebook but had initially been unaware of the settings required to stop strangers from viewing the information.
“She was just anxious about whether anyone would show up to her birthday,” he told the Telegraph.
Police said it appeared the girl’s original post had been reposted by an “unknown person” and this had gone viral.
“The father has given us an undertaking that he will have the Facebook page removed and the party will definitely not be going on,” police Inspector Terry Dalton told ABC Radio. “There will be no party at that address.
“The only thing that anybody who turns up on that street will be met by will be some police vehicles patrolling the area.”