Google is blaming a hacker from China for tapping into hundreds of personal Gmail accounts across the globe.
Some U.S. government officials even fell victim to the scheme.
A representative from Google says the account hijackings were a result of stolen passwords.
The online search engine company suspects the hacker secretly installed malware on victims' computers when they responded to an email from a source they thought they could trust.
The hacker was reportedly attempting to monitor the victims' e-mails, and some users' forwarding settings were altered.
Google says it notified the victims and disrupted the campaign.
The company is urging users to beef up their online security.
Gmail's security systems were not compromised.