Authorities arrested 56 people during a massive crackdown on a postal theft fraud operation in Southern California.

The suspects were involved in a scheme that resulted in the theft of almost $5 million, victimizing hundreds of residents, according to the California Department of Justice.

Authorities say the suspects allegedly altered stolen checks, deposited them into bank accounts and quickly withdrew them from ATMs before officials caught wind of the forgeries.

The multi-million-dollar scheme operated out of multiple counties, including Los Angeles County and San Bernardino Counties, beginning in 2018, officials said.

On Oct. 6 and 7, 34 teams of local, state and federal agencies “carried out a wide-ranging law enforcement sweep across the counties of Los Angeles and San Bernardino, with the arrests being the result of a years-long operation by the U.S. Postal Inspection Service,” the DOJ said.

The suspects used hundreds of banks to carry out the crimes, victimizing 750 Californians, authorities said.

Investigators believe the stolen money was also used to fund other criminal operations.

“Let this be a strong warning to anyone seeking to steal people’s hard-earned money: We will find you, and we will hold you accountable,” said Attorney Rob General Bonta.

“Today is a victory, not only for the multitude of law enforcement agencies who dismantled this organization, but for the citizens in California,” said Carroll Harris, inspector in charge of the Los Angeles Division of the U.S. Postal Inspection Service.

The suspects are facing charges of aggravated white collar crime in excess of $500,000, aggravated white collar crime in excess of $100,000, conspiracy to commit grand theft by false pretenses, forgery relating to an item exceeding $950, money laundering and grand theft by false pretense.