Internet apocalypse: Google blackout sees global web traffic plunge by 40 per cent All services down for five minutes in 'unprecedented' outage Experts 'nervously' trying to find out the cause of mystery Google headquarters in London Worldwide internet traffic plunged by about 40 per cent as Google services suffered an 'unprecedented' black-out, web experts have revealed. The tech company said all of its services from Google Search to Gmail to YouTube to Google Drive went down for between one and five minutes last night but it refused to elaborate on the reasons why. According to web analytics firm GoSquared, global internet traffic fell by around 40% during the black-out, reflecting Google's massive grip on the web. 'That's huge,' GoSquared developer Simon Tabor told Sky News. As internet users, our reliance on Google.com being up is huge. 'It's also of note that pageviews spiked shortly afterwards, as users managed to get to their destination.' A message on the Google Apps Dashboard showed all of its services were hit. 'We're aware of a problem with Gmail affecting a significant subset of users. The affected users are able to access Gmail, but are seeing error messages and/or other unexpected behaviour,' it said. A later message said: 'Between 15:51 and 15:52 PDT, 50% to 70% of requests to Google received errors; service was mostly restored one minute later, and entirely restored after four minutes.' Experts said the outage had cost the company about £330,000 and that the event was unheard of. They are baffled by the cause. Computer website writer Neil McAllister added said technical experts would be 'nervous' as they sought to find out what happened. 'Exactly how an operation like Google's can even go dark like that, all at once, is anybody's guess,' he said. The Google data center in Douglas Country, Georgia. The company is refusing to reveal what caused the 'unprecedented' blackout