Wells Fargo confirmed on Thursday that there were system-wide problems causing outages on its online banking platforms and mobile banking app.

«We apologize to our customers who may be experiencing an issue with our online banking and mobile app. Thanks for your patience while we research this issue,» the bank tweeted on Thursday morning.

It followed up 40 minutes later with another message: «We’re experiencing a systems issue that is causing intermittent outages, and we’re working to restore services as soon as possible. We apologize for the inconvenience.»

Wells Fargo did not immediately respond to a request for comment.

PHOTO: The logo of American multinational financial services company Wells Fargo is displayed on a smartphone on Jan. 02, 2019, in Berlin.Photothek via Getty Images
The logo of American multinational financial services company Wells Fargo is displayed on a smartphone on Jan. 02, 2019, in Berlin.

Customers experiencing issues also tweeted about their problems with using credit and debit cards.

«Direct deposits have been rejected people say, and on social media people are not able to use their cards. Wells Fargo has message to call for support or visit an ATM but those two are down. Branches cannot access accounts either. It’s not just the online banking/mobile app,» one Twitter user wrote.

The cause and scope of the problem were still unclear on Thursday morning, but there several possible explanations including problems with its IT infrastructure or a possible cybersecurity attack, experts said.

«Banks and financial institutions are under attack continuously. Often, a slowdown means they’re under a particular attack so their defenses are up as they are sorting through what’s going on. They could be running additional security checks,» Lisa Ellis, an analyst who leads payments, processors, and IT services coverage at the research firm MoffettNathanson, told ABC News.

Bank operations may sometimes be slowed down during a cyber attack, including when its a «denial of service» attack or a «brute force» attack, which happens when the website «is getting pinged, say, rather than 1,000 customers a minute, it’s 100 times that, or orders of magnitude more,» Ellis, whose company does not work with Wells Fargo, told ABC News.

«I’m not suggesting that’s what’s going on in this instance, but it could be what’s going on,» Ellis added. «Banks are using the public internet’s backbone, so it could just as well be a problem with its own IT infrastructure» or a provider having slow service.