Gmail service went down worldwide Friday afternoon, frustrating millions of users. The outage also affected other Google services such as Hangouts and Google+.

Google's apps dashboard initially showed all Google services in the green, but it was updated at around 2:20 p.m. ET to show a service disruption for Gmail. Gmail stopped working for both web and mobile apps as well as third-party clients such as Apple Mail, suggesting that the entire back-end (IMAP) service was affected.

See also: 5 Things to Do While Gmail is Down

Judging from the response on Twitter, the outage appeared to be worldwide and affected other Google services as well. Hangouts and Google+ both stopped working; some Google Drive users were reporting connection issues, too. The Google homepage remained unaffected, though, as were Google's main search products. Google Calendar appeared unaffected as well.

Google has not yet made a statement about the outage apart form the app dashboard, and the official Gmail Twitter account has been silent since Wednesday.

Ironically, Google's site reliability team was answering questions in a Reddit AMA at the time of the outage. They didn't address the current outage directly, but one team member responded to a Reddit user about how much "freaking out" the team does during an outage.

"Very little freaking out, actually," the Google employee wrote. "We have a well-oiled process for this that all services use — we use thoroughly documented incident management procedures, so people understand their role explicitly and can act very quickly."

The full effects of the outage won't be known until Google addresses how extensive it was, but since it affected Google users worldwide, the cost to business productivity is potentially vast. According to a recent InformationWeek survey, 29% of large companies supported Gmail or had plans to, but 63% of small businesses do. A Gartner study from last spring showed Google making significant inroads against Microsoft Office for businesses productivity suites.

Reports flooded in on Twitter about the outage. Many expressed frustration and dismay, although a few found humor in the situation.

Gmail is down. World productivity is slowing grinding to a halt. — Aaron Levie (@levie) January 24, 2014

Gmail isn't really down, it's just making a copy of your email for the NSA. — Geeks of Doom (@geeksofdoom) January 24, 2014

Oh man, is Gmail down? Your move @Yahoo — Omar Bilal Akhtar (@obakhtar) January 24, 2014

Gmail is down so we're launching Dmail. You come to us & eat pancakes while we read you old love letters. — Denny's (@DennysDiner) January 24, 2014

The polite thing for Google to do when Gmail is down would be to send an email stating so. — Jared Spool (@jmspool) January 24, 2014

Hey so Gmail is down. Do you guys mind if use Twitter for my business communications today instead? — Josh McHugh (@Mc_Huge) January 24, 2014

Yahoo, too, tried to get in on the fun by tweeting about the outage, but immediately apologized for its "bad judgment."

This is far from the first Gmail outage. The service was crippled for days during a major outage in 2009, and has suffered temporary disruptions since then, but they have rarely lasted more than a few hours, and are sometimes limited to a subset of users.

UPDATE, Jan. 24, 3:05 p.m. ET Gmail appears to be back online for most users.

UPDATE, Jan. 24, 9 p.m. ET Google responded to the outage in a blog post, in which the company's VP of Engineering Ben Treynor blamed a software bug for the breakdown. He also wrote that his team is in the process of updating systems to prevent such a service failure in the future.