A SWAT team assisted in the raid, which took place about 3:30 a.m. in the 2300 block of Pacific Avenue after reports of suspicious activity, according to the Long Beach Police Department.
It was not immediately clear how many of the detained individuals were formally arrested.
Plainclothes officers and detectives were seen removing gaming machines from the premises.
Wednesday's operation followed a gambling bust last week at a storefront on nearby Anaheim Street, where Long Beach police arrested eight people and confiscated two guns and $12,000 in cash.
Whether the two locations were connected was unknown.