Yahoo services went down for several hours on Thursday, drawing ire from thousands of its email users who were given no idea how long the outage would last.
Downdetector, a website that provides information on online outages, had received more than 5,000 reports of problems related to Yahoo Mail by 2.a.m ET. Some 300 users also reported problems with other Yahoo services, according to Downdetector.
According to one Twitter user, Yahoo had been down for "well over 3 hours" in Australia. Most of the complaints originated in Europe.
"We understand how difficult this must be for you. We are working especially hard to fix this. Please stay tuned for updates," Yahoo tweeted from its official customer care account on Thursday shortly before 4 a.m ET.
About an hour later, the company posted another tweet to say it had identified the issue but could not say how long it would take to resolve.
Yahoo's customer service webpage — help.yahoo.com — also went down for a time, displaying the message, "Thank you for your patience. Our engineers are working quickly to resolve the issue."
In 2013, a data breach at Yahoo compromised the accounts of the 3 billion users it had at the time. Yahoo parent company Oath, a subsidiary of Verizon, could not immediately be reached for comment on the cause of Thursday's outage.