Regions Bank was hit with a cyberattack Thursday afternoon that jammed online and mobile banking and left some customers unable to access their accounts.

The $121 billion-asset unit of Regions Financial (RF) took to social media to tell customers it was working to resolve the slowdown. "We are currently under cyber attack and our website and Online Banking are experiencing issues," Regions tweeted. "We apologize for any inconvenience."

Regions spokesman Mel Campbell said in an email the attack did not threaten customers' personal or financial information and that company's automated teller machines and branches remained available for customers who were unable to log in to their accounts.

The assault represents at least the second cyberattack the company has acknowledged and comes amid a surge in electronic assaults that have slowed service at some of the nation's largest financial institutions.

Last week, Wells Fargo (WFC) endured the second cyberattack the company had acknowledged in as many weeks. Since March, JPMorgan Chase (JPM), American Express (AXP), BB&T (BBT) and TD Bank have weathered similar assaults as well. KeyCorp (KEY) also said its websites had experienced intermittent slowdowns during that time.

The al-Qassam Cyber Fighters, a group of hacktivists who have claimed responsibility for the attacks, said in an email Tuesday that the group's latest targets include Regions, BB&T, Wells Fargo, American Express, KeyCorp and SunTrust (STI).

The group has vowed to keep up the attacks until trailers for an anti-Muslim film are taken down from YouTube.