British Airways said on Thursday that it is investigating the theft of customer data from its website, and the airline’s mobile app.

According to the company, between August 21 2018 and September 5 2018, the personal and financial details of customers making bookings on and the airline’s app were compromised. While the company did not go into specifics, The Guardian reports that 380,000 “payment cards” were affected.

British Airways stated that the breach has been resolved and they have notified the police and relevant authorities.

The company also said it is communicating with affected customers and advised customers who believe they may have been affected by this incident to contact their banks or credit card providers and follow their recommended advice.