The Pomona Police Department along with units with the Los Angeles County District Attorney's Office conducted a search warrant at an illegal casino in the 600 block of N. Indian Hill Boulevard around 5 a.m.
Police said when officers went in, they discovered eight different casino tables.
A total of 40 people were detained and several guns along with "large amounts of money" were confiscated, according to police.
Details surrounding the seizure weren't immediately released.
The incident remains under investigation.
This is a developing story. This article will continue to be updated as more information become available.