Editor's Note: Story updated 11:40 a.m. Eastern U.S. time with new statement from TfL.

The National Crime Agency announced on Thursday it had arrested a teenager in connection to a cyberattack targeting Transport for London (TfL), the government body responsible for the transport network in Britain’s capital.

The suspect, a 17-year-old male, has not been named. According to the NCA, he was detained on Computer Misuse Act offenses on September 5 and has since been bailed.

TfL’s website states it is still dealing with “an ongoing cyber security incident” after initially identifying suspicious activity on September 1. The page originally stated that there was no evidence customer data was accessed. That line has been removed, although a spokesperson declined to confirm to Recorded Future News whether this was due to evidence being uncovered.

However in an updated statement on Thursday, TfL confirmed: “Our investigations have identified that certain customer data has been accessed. This includes some customer names and contact details, including email addresses and home addresses where provided.”

It warned that some data related to Oyster cards — the smart cards used to pay on London’s transport networks — may have been accessed, including bank account numbers and sort codes for around 5,000 customers.

Announcing the arrest, Paul Foster, the head of the NCA’s National Cyber Crime Unit, said: “We have been working at pace to support Transport for London following a cyber attack on their network, and to identify the criminal actors responsible.”

“Attacks on public infrastructure such as this can be hugely disruptive and lead to severe consequences for local communities and national systems,” said Foster.

“The swift response by TfL following the incident has enabled us to act quickly, and we are grateful for their continued co-operation with our investigation, which remains ongoing.”