It was reported by users in Reddit that MyEtherWallet has been hacked. The news is confirmed by MyEtherWallet via twitter, commenting that a couple of DNS servers were hijacked resulting in myetherwallet.com users being redirected to a phishing site.
According to Reddit users, hackers placed a security SSL mismatch which was redirecting users to a different domain. Right now it appears that people are being affected via LOGIN only. Users recommended people to not login and to only view balances via Etherscan or another explorer. In cases where people need to move funds, it is best to use other wallets and to only use MyEtherWallet offline.
The reason has not been confirmed but users are debating about what has caused this episode, with some pointing out that it could have been an issue with Google DNS. We will continue following the news as it develops.