Unknown threat actors have caused a security incident at London-based outsourcing services provider Capita, which prevented employees from accessing their internal Microsoft Office 365 applications, reports BleepingComputer. The company, which employs 50,000 specialists providing services in the fields of healthcare, IT and government services, among others, said in a press release that the attack occurred at 4 a.m. Friday and was detected three hours later when workers tried to log in to the network. According to Capita, the incident disrupted some parts of its network, but remediation actions swiftly contained the issue and it did not detect signs of exposure of data belonging to its employees, customers, or suppliers. The company said it was proceeding to bring Microsoft Office 365 access and client services back up. It said there was no disruption to most of its customer-facing services, but some known clients of Capita, including the U.K. boroughs of Dagenham, Barking, Barnet, and the South Oxfordshire council, have issued notices of lost telephone and email connectivity.