Google is looking into an outage that caused Gmail, an email service used by hundreds of millions of people around the world, according to Reuters.

Gmail service resumed for some users after the outage but many people are still without service at press time.

People trying to login to their email received this message instead: "We're sorry, but your Gmail account is temporarily unavailable. We apologize for the inconvenience and suggest trying again in a few minutes."

It is currently unclear what caused the outage, which has affected people in the U.K., India, and the U.S. at least.

"We're investigating reports of an issue with Gmail. We will provide more information shortly," the company said on its "App Status" dashboard.

Yahoo Inc. decided to take a shot at its rival by posting a screenshot of the error page on Twitter.

The company's Google+ social network and YouTube video service was *blank as well.

Google has not commented on the issue just yet.

Gmail is temporarily unavailable pic.twitter.com/KLNxcQ9zUP

— Yahoo (@Yahoo) January 24, 2014

The last time Gmail went down was Sept. 24, 2013, according to Forbes. The problem affected 50 percent of its users.

Google has not said how many people have been affected by the latest problem.

See Now: OnePlus 6: How Different Will It Be From OnePlus 5?