(KRON) — In the Bay Area, 10 people have been arrested for mail theft and violence against mail carriers, prosecutors announced Tuesday. Now, federal investigators are tripling a reward to help catch more criminals behind these acts.

Federal investigators said attacks on postal workers are growing and thieves are taking off with packages and keys to entire apartment buildings. A $150,000 reward is now being offered for tips leading to arrests and convictions.

“These keys are now the keys to prison if you are found with these. It’s simply not worth it,” said U.S. Northern District Attorney Ismail J. Ramsey.

Federal investigators are going after criminals to discourage more of them from continuing to target and assault mail carriers.

They say it’s a growing problem that comes with a heavy price for those who are caught. One man arrested in Antioch now faces a maximum of 10 years in prison for allegedly stealing mail keys and another 25 years each for two armed robberies.

“To any copycats or wannabes out there who might consider robbing a postal worker, I ask that you consider the years you will face in federal prison, the price on your head, and that postal inspectors will not stop hunting you,” said U.S. Postal Inspector in Charge Rafael Nunez.

Union representatives say some mail carrier members now suffer from PTSD and are not coming back to work.

“Letter carriers don’t wake up in the morning thinking someone is going to stick a gun in their face,” said Edward Fletcher, president of Letter Carriers Branch East Bay 1111.

A reward for tips leading to arrests and convictions has gone up from $50,000 to $150,000.

Authorities hope this will help with investigations, and that the prison time will help dissuade would-be thieves. But at the end of the day, it’s about keeping the mail, and the postal workers safe.

“Our carriers are just trying to deliver your mail to you, and they are a part of the community and they’re afraid. This has to stop,” said Karen Eshabarr, president of Letter Carriers SF Branch 214.

Prosecutors said whatever the motivation, whatever today’s message should be clear, that unless this behavior stops, they will keep going after these criminals.