The four - affiliated with the Philadelphia mob - appeared to be the ringleaders, with six employees of the Borgata Hotel Casino & Spa also among those arrested, said the source, who spoke on condition of anonymity because he was not authorized to comment on the case.
Details on charges were not immediately available. Five other people were being sought Wednesday.
State Attorney General Anne Milgram scheduled an afternoon news conference to discuss the case.
Borgata spokesman Michael Facenda said he could not comment.
The state Casino Control Commission was expected to take disciplinary action against the casino workers who were arrested, commission spokesman Daniel Heneghan said.
"I'm certain that any Borgata employees that were arrested, the Division of Gaming Enforcement will file complaints to revoke their licenses," he said.
If the charges are proven, it would be among the most serious mob incursions into the Atlantic City casino industry since the first casino opened in 1978. Fear of organized crime prompted New Jersey to institute tight controls when legal gambling began, but regulations have been loosened over the years.
The anxieties were expressed in a now-famous speech by then-Gov. Brendan T. Byrne when he signed the law authorizing casinos on June 2, 1977: "I've said it before and I will repeat it again to organized crime: Keep your filthy hands off Atlantic City. Keep the hell out of our state!"
Unlike Las Vegas, Atlantic City has no legal sports book.
This is the second high-profile sports betting charge in New Jersey in the last two years. In 2006, a state trooper, NHL hockey coach Rick Tocchet and a third man were charged with running a sports gambling ring. All later pleaded guilty.