British electronics superstore chain Dixons Carphone–one of Europe’s biggest–is dealing with a massive data breach. Nearly six million payment cards may have been affected.

In a review of the company’s systems and data last week, evidence surfaced that there was a cyber intrusion that dated back to July 2017, according to Reuters. The incident marks the second major cyberattack the company has suffered in three years.

A spokesperson for the National Cyber Security Centre (NCSC) told the BBC that it was “working with Dixons Carphone and other agencies to understand how this data breach has affected people in the UK and advise on mitigation measures.” Meanwhile, the NCSC is providing guidance on its website for the retailer’s customers.

In all, 5.9 million credit cards and 1.2 million personal data records were involved in the data breach. Reuters reports, “5.8 million of these cards had chip and pin protection and the data accessed contained neither pin codes, card verification values nor any authentication data that would enable cardholder identification or purchases to be made.” But, Reuters adds, “105,000 non-EU issued payment cards which do not have chip and pin protection had been compromised.”

So far, reports indicate that there has been no evidence of fraudulent use of the cards following the breach.

Get the full story at Reuters.