Ahold Delhaize said Monday, Oct. 19, that the suspicious activity it first disclosed on Oct. 12 was a cyberattack, one that led the grocery group to take websites, apps and other systems offline across most of its brands in the U.S. and Europe. The company filed a formal report with Dutch police the same day, according to its corporate newsroom .

Its investigation "confirmed the suspicious activity resulted from the malicious actions of others," the company said. Ahold Delhaize brought in outside cybersecurity experts after detecting the activity and notified the Dutch National Cyber Security Centre within 24 hours.

Stores open, shelves thin

Stores stayed open throughout, but the shutdown hit online ordering, home delivery and, in the Netherlands, the supply chain behind the shelves. Work at some of Albert Heijn's six Dutch distribution centers stopped completely on Oct. 12, leaving gaps in fresh produce and other goods, DutchNews.nl reported. The parent company said on Oct.…