Story highlights Suspected Hong Kong triads target Transformers filming second time in a week

Four men demand money from production team; one arrested, three escape

Shakedown follows assault on Transformers director Michael Bay for $13,000

Triad-related crimes rose 15% between 2010 and 2012, says Hong Kong Police Force

For the second time in a week, suspected Hong Kong organized crime syndicates -- known better as triads -- have targeted the production of "Transformers: Age of Extinction" being filmed in the Chinese territory.

Four men attempted to extort an undisclosed sum of money from a crew member inspecting a rooftop shot location in the district of Kowloon Tuesday, the Hong Kong Police told CNN.

Police arrested and charged one 35-year old man with blackmail but his three partners remain at-large.

The attempted shakedown follows a suspected triad incident October 17 in which two men assaulted Transformers director Michael Bay

Bay, 48, explained that every vendor that experienced disruptions from filming in the area "got paid a fair price for our inconvenience" but one man "wanted four times that amount" -- around $13,000 (100,000 Hong Kong dollars).

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"I personally told this man and his friends to forget it," said Bay. "We were not going to let him extort us. He didn't like that answer."

The man returned an hour later, "carrying a long air-conditioner unit," added Bay. "He walked right up to me and tried to smack my face, but I ducked threw the air unit on the floor and pushed him away."

Hong Kong police arrested two brothers in connection with the incident.

In both episodes, triads -- known for their dealings in smuggling, prostitution and illegal gambling -- are believed to be involved.

"The two incidents associated with Transformers are indicative of low-level attempts to extort money from a big production by persons who may be triad members," said Steve Vickers, former head of the Royal Hong Kong Police Force's Criminal Intelligence Bureau and now CEO of Steve Vickers and Associates, a specialist political and corporate risk consultancy.

"The separate side of this is that the triad control of the movie industry in Hong Kong is a very complicated issue and has been in place for many years," added Vickers. "The triads strangle the oxygen out of the local movie scene. They're not just extorting people for money. It's control of movies, starlets and distribution."

In recent years, triad-related crimes in general have been on the rise, according to crime statistics from the Hong Kong Police Force

For three years in a row, from 2010 to 2012, the number of triad-linked incidents rose nearly 15%. Most recent data for the first half of 2013, however, shows 988 triad-related crimes -- the second lowest reported number for the same time period over the past decade.

But "reported crime is not an accurate measure of triad influence," said Vickers. "Triad related crimes are under reported."