Many Americans scrambled to protect their personal information online after learning of the Heartbleed Internet flaw, and some believe their data was stolen, a survey showed Wednesday.

The Pew Research Center report found 39 percent of US Internet users took steps to protect their data such as changing passwords or cancelling accounts.

Six percent of the online users said they believed they lost data as a result of Heartbleed, Pew found.

The Heartbleed flaw, which was undetected for more than two years, allowed hackers snatch packets of data from working memory in computers, creating the potential for them to steal passwords, encryption keys or other valuable information.

Most websites patched the flaw as part of a rush to allay concerns about the security of online information.

The Pew survey found mixed views on security of personal information online:

Roughly half -- 46 percent -- said they believe their information is "somewhat secure," while 23 percent said their data was "very secure" and 26 percent "not too secure" or "not at all secure."

The survey found 60 percent of the American public had heard at least a little about Heartbleed, including 64 percent of Internet users.