More than 80 people have been charged in a scheme in which the suspects deposited checks stolen through the U.S. Postal Service into various bank accounts, totaling nearly $5 million in losses in a widespread mail theft operation, authorities said Friday. 

The fraud scheme began in 2018 when people deposited altered checks stolen from the mail into "numerous" bank accounts, said Carroll Harris, the inspector in charge of the Los Angeles division of the U.S. Postal Inspection Service.

"The suspects would swiftly withdraw the money before the financial institutions discovered the checks were forged," he said during a news briefing to announce the charges. "This investigation identified hundreds of victims across California."

2 DEAD AFTER PLANE SLAMS INTO RUNWAY IN CA

The ringleaders behind the operation recruited people on social media to open bank accounts or use their own accounts to deposit the fraudulent checks, authorities said. Los Angeles County Sheriff Alex Villanueva said two street gangs were involved in the scheme.

Thieves would steal the checks from the mail and remove the names and replace them with fraudulent names, he said. 

The banks reported the thefts to authorities, prompting a years-long investigation. Investigators said 769 victims were affected and that the stolen funds were used to fund other criminal activity. 

On Thursday and Friday, authorities from various law enforcement agencies conducted sweeps throughout Los Angeles and San Bernardino counties.

The California Department of Justice said 56 people have been arrested. Those charged face felony grand theft, money laundering, and conspiracy charges.

"We're talking birthday checks from grandma. Hard-earned paychecks from employers, stolen, and never received," California Attorney General Rob Bonta said Friday. "There needs to be real accountability for these crimes, and there will be."

Bonta's office will file 330 felony charges against 88 defendants, he said.