The "Iranian Cyber Army" is apparently behind the hacking of Twitter. When you tried to access the site you were greeted with this image.
Picture embedded below.
"U.S.A Think They Controlling And Managing Internet By Their Access , But They Don’t , We Control And Manage Internet By Our Power , So Do Not Try To Stimulation Iranian Peoples To ………….. NOW WHICH COUNTRY IN EMBARGO LIST? IRAN?USA? WE PUSH THEM IN EMBARGO LIST ;) Take Care."
Everything now is back to normal.
"As we tweeted a bit ago, Twitter's DNS records were temporarily compromised tonight but have now been fixed. As some noticed, Twitter.com was redirected for a while but API and platform applications were working. We will update with more information and details once we've investigated more fully."