Google confirmed the problem and the outage around 1:30 PM EST and said that this issue has only affected around 2 percent of its users. However, considering the size of Gmail users at 350 million, the figure roughly points to around 7 million users.
Right before 2:00 PM EST, Google Apps has announced that all problems have been fixed and everything should be back to normal within a few minutes.
Upon checking, and scanning various social media, it looks like that Gmail is already good, up and running normally. However, as of press time, no official explanation has been released by the company to explain what caused the outage.