OP's 2 Factor Authentication got hacked also including his login details. There are several cases of accounts being hacked even 2FA is enable.

http://www.reddit.com/r/Bitcoin/comments/1ubv3o/my_blockchaininfo_wallet_hacked_strong_unique/

http://www.reddit.com/r/Bitcoin/comments/1zjp8h/my_account_on_bitstamp_got_hacked_i_had_2fa_and/

http://www.reddit.com/r/Bitcoin/comments/1xava5/my_coinbase_account_was_drained_too_i_had_2fa/