Dutch bitcoin broker Bitonic said unauthorized parties gained access to part of its systems overnight and stole small amounts of bitcoin from three customers. The company said it would fully compensate those customers. It also said an attacker altered login credentials for two accounts.

Bitonic said it had fixed the vulnerability, logged all customers out of its website and app as a precaution, and temporarily took affected systems and its internet-connected hot wallet offline. The service is now fully available, while bitcoin withdrawals are subject to extra checks and may take longer. Bitonic said its offline cold wallets were unaffected and that it cannot rule out access to other customers’ personal data, although current information does not indicate this happened. The company is continuing to investigate the technical cause and scope of the breach.