Updated

Australian police arrested a man after he allegedly posted an online threat saying a shooting attack would take place at a Los Angeles mall, officials said Friday.

Jarrad Willis, 20, of Melbourne, was arrested Friday night local time in Australia.

Los Angeles Police Department detectives traced the address of his Internet provider to Australia. Willis allegedly said the attack would happen Friday at The Grove mall near Beverly Hills.

Police Deputy Chief Michael Downing said the warning was posted on 4chan.org, an image-based bulletin board featuring adult content and blog comments. The posting featured a picture of a man holding a shotgun in a gun store, Downing said.

"He says, `I am going to shoot and kill as many people as I can until which time I am incapacitated or killed by the police,"' Downing said. The posting has been removed.

The LAPD contacted Australian police, who tracked the location of the computer allegedly used for the threat. Downing said Australian police already knew Willis, "because he had done things like this in the past."

Downing said there was no indication Willis, who has never been to the United States, had any way of carrying out the threat, which came after Wednesday's mall shooting in Omaha, Nebraska, that left eight holiday shoppers and the gunman dead.

Downing said he did not know why Willis posted the alleged threat.

Willis has been charged in Australia with creating a false belief — a violation of Australian law. Police said other charges are likely.

It was not immediately known if Willis had an attorney.

Downing said additional patrol units were posted at the mall until it was determined that Willis had no way of carrying out the alleged threat.

Willis faces up to five years in prison. As part of the prosecution, Australian authorities will seek up to US$100,000 from him, the estimated cost of the LAPD's investigation, Downing said.