Twitter is glowing red-hot with anger from frustrated Verizon users because of a widespread system outage that currently affects thousands of Verizon customers in many parts of the U.S.

The Verge first reported the outage Thursday, citing several customer complaints with the hashtag #VerizonOutage that flooded people's Twitter feeds. Users are reportedly unable to access Verizon's self-serve online services, which prevented them from doing things such as accessing and paying their bills, activating their phones or upgrading it at physical Verizon stores in several states, although customers can still continue to use their phones for calls and data services.

Verizon confirmed that it has been experiencing downtime Friday and assured customers that the carrier is doing its best to resolve the issue. The company did not specify what problems it is dealing with exactly but said in a statement that it has already identified the issue.

"We are still experiencing issues with our billing system that [are] affecting customer accounts, mostly in the Northeast, Midwest and some Southern states. This is an internal billing system issue that doesn't affect the network's ability to connect calls, deliver text messages or use data services," writes Verizon spokesperson Laura Merritt. "This is taking longer to resolve than any of us would like. The good news is that we have identified the issue and are working hard to ensure we have the right fix to solve it."

The number of customers affected by the downtime is still unknown, but complaints posted on Twitter come from various locations from New York, Ohio, Illinois, New Jersey, Tennessee and New Hampshire. A number of customers have also said that they have been experiencing downtime for nearly two days.

"The #VerizonOutage has been going on for 48+ hours. Reps keep saying it's a 'system update.' Terrible brand management overall," says Verizon customer Sara Miller.

"Hey Verizon, Verizon Support, I have paperless bills & your system has been down for 2 days online/mobile. Bill is due today. How do I pay?!" asks Kari Londo.

A few Twitter users have reported that their services have been put back up around 3 a.m. EST, suggesting that Verizon's technical team is hard at work in fixing the unidentified issue. However, many customers still say that an error message is all they see on their My Verizon accounts.

Although Verizon has promised to update its customers on the issue, the situation is still in the air as America's largest mobile carrier has yet to explain what's wrong and how it's working on it.