The IRS says there are scammers who have intercepted the tax returns of people who think they filed online, and redirected the refunds into their own accounts as they file the stolen returns with the IRS.
How? Imitation web sites that offer free filing are sent to people with a link -- and the link takes the victim to a web site that looks like a real IRS site, but actually leads to a place that the scammers can take the information.
The way you avoid getting scammed? Never, never, never click on a e-mail link that will be recording any personal information. If you want to file free, use Google, find the IRS web site, and start there. Do not use the tempting link in e-mail. Just don't.