Twitter was down as of 8:17pm EST in New York State. Users who tried to go to the twitter site at https://www.twitter.com received an https 503 error. 503 errors are for “service unavailable”, and typically appear when a website is having issues such as a server RAM leak, DNS issues, or problems with their backend database.
No word yet as to whether this is part of some devious Russian plot to bring down Western society, the result of a revenge hack to try to strike back at the US for sanctions against Russia, an underhanded move by the North Koreans, similar to when Kim Jong Un ordered the hacking of SONY, or just random cock-up that happened because Jack Dorsey got stingy with server maintenance.