Artichoke Joe's Casino is closed indefinitely after federal agents raided the card room Wednesday morning over allegations that loan sharks advanced money to broke players at exorbitant rates and then threatened them with violence to get repayment.

The Oaks Card Club in Emeryville was also shut down as part of the operation by state and federal law enforcement agents, which targeted Asian gangs that were allegedly involved in the scam at both locations, according to a source close to the investigation. Officials also believe drugs were distributed on the floor of at least one of the casinos, but it was not clear Wednesday which one.

The source said players who ran out of money but wanted to keep gambling at Artichoke Joe's were approached by loan sharks, who may have been connected to the club.

The loans were granted at high interest rates, however. When the gamblers wouldn't or couldn't pay, they were threatened, but it's not clear if anyone was harmed for failing to pay up, the source said.

State law enforcement officials were on the case, which involved surveillance and the use of informants, for at least two years

Both card rooms are subject to an emergency closure. State agents have two days to file a formal complaint, and Artichoke Joe's is entitled to a hearing before the California Gambling Control Commission within 10 days. The commission could decide to extend the closure or allow the card room to reopen.

Alan Titus, an attorney for the owners of Artichoke Joe's, did not respond to a phone message seeking comment.

If the card club remains shuttered, San Bruno could be left with an extra $1.4 million hole in its roughly $31 million budget. That's the amount the club was due to pay in taxes to the city for the 2010 fiscal year.

City leaders have begun preparing the budget for the next fiscal year, which starts July 1, and anticipate a shortfall of at least $1 million, not including any losses from a possible Artichoke Joe's closure.

On Wednesday morning, San Mateo County deputies and San Bruno police guarded the front door of the card room as agents wearing jackets marked "FBI" walked in and out. An FBI spokeswoman on scene said the club had been raided as part of a Bay Area-wide criminal investigation that included the U.S. Attorney's Office, the Drug Enforcement Administration, the IRS and the California Department of Justice's Bureau of Gaming Control.

Lucky Chances Casino in Colma, the only other card room in San Mateo County, was not raided Wednesday.

Patrons of Artichoke Joe's, who were turned away from the closed card room Wednesday, as well as several employees, said they had no idea the raid was coming and didn't notice anything amiss before it happened. Two men who said they worked as security guards at the casino sat near one of the entrances but said they hadn't heard anything from the owners.

"The casino is closed, so I have to go home," said John Jeon, of San Jose, who had come to gamble. "It's raining today, so I came to spend some money -- I mean some time."

Artichoke Joe's has been operating in San Bruno since 1916 and remains under the control of the Sammut family, according to the card room's website. The 20,000-square-foot casino claimed to be open 24 hours a day 365 days a year.

It draws its name from a quote of its founder, Joseph Sammut. According to the website, he was asked in his early days of operation how he would pay if he lost a big bet. "In artichoke leaves," Sammut reputedly said.

Contact Joshua Melvin at 650-348-4335.