Staff at Letterkenny-based Optum were informed by email of the horrific killing of their CEO Brian Thompson.
Mr Thompson, aged 50, was shot dead in New York this morning.
Mr Thompson, who was the CEO of UnitedHealthcare, died at the scene.
Optum is a subsidiary of the UnitedHealth Group.
The businessman was murdered outside the Hilton Hotel as he traveled to UnitedHealthcare’s annual investor conference.
A gunman is reported to have been laying in wait before opening fire on Mr Thompson.
The assailant was said to have fled on a bicycle and is believed to have headed to Central Park.
Mr Thompson visited Optum employees in Letterkenny on several occasions, including an Optum town hall meeting held at An Danlann on the ATU campus.
