British Airways employees are investigating a data breach that compromised customer financial information for more than two weeks.

Airline officials said the breach started around 11 p.m. BST on Aug. 21 and continued until 9:45 p.m. BST on Sept. 6. During that time, the personal and financial information of customers who booked flights on British Airways’s website or mobile app was compromised.

“The breach has been resolved and our website is working normally,” company officials said Thursday in a statement. “We are deeply sorry for the disruption that this criminal activity has caused. We take the protection of our customers’ data very seriously.”

The data breach compromised the credit or debit card numbers of at least 380,000 British Airways customers, Sky News reported.

The company has contacted authorities to investigate the incident.

British Airways employees advised people who believe they might have been affected by the incident to contact their banks or credit card providers.