Zions Bank sent letters to some of it customers this week notifying them of an online data breach.

“We recently learned of unauthorized access to our computer network on or around June 1, 2019,” according to the July 22 letter. ″As a result we believe some personal information of some of our online banking customers may have been improperly viewed or acquired.”

The letter did not disclose how many customers were affected. But James Abbott, director of external communications, said information from “a limited number" of customers "may have been viewed or accessed by an unauthorized user of our data network.”

User names, email addresses, account numbers — as well as Social Security or tax numbers if used as identification — were included in the accessed information.

“Passwords," the letter emphasized, “were not included in the data that may have been accessed.”

After it learned of the breach, Zions contacted forensic experts to determine the scope of the intrusion. Federal law enforcement and banking regulators also were notified.

“We quickly took measures to enhance customer security,” the letter states, "and are implementing enhanced internal monitoring on accounts designed to protect them from illicit actions.”

The bank currently has no evidence that “personal information has been misused.”

Customers who may have been affected are being asked to change their logins and passwords and to enroll in identify theft protection, which Zions is providing free for two years.