The Irish Data Protection Commission announced Wednesday that it had launched an investigation into Facebook, likely the first such inquiry of a major tech company since the implementation of the European Union’s General Data Protection Regulation back in May.

The IDPC’s investigation, which was announced via tweet, was spurred by Facebook’s announcement Sept. 28 that a data breach on the platform impacted approximately 50 million users, less than 10 percent of whom are reported to be EU residents. The IDPC is responsible for upholding EU data privacy laws in Ireland, where Facebook’s European headquarters are located.