Jan. 21 (UPI) — Three crew members of a medical helicopter died after their aircraft crashed in Oklahoma, their company said Sunday.

The Air Evac Lifeteam crew was returning to their Weatherford, Okla., base after transporting a patient to Oklahoma City late Saturday when the Bell 206L-3 helicopter they were aboard crashed at about 11:23 p.m.

“Our primary focus is on supporting the families and our team members,” Air Evac Lifeteam said in a statement on social media announcing the deaths.

The names of the victims were being withheld out of respect for their privacy and that of the families, it said.

The National Transportation Safety Board, which is investigating the incident, said the crash occurred near Hydro, Okla., located just outside Weatherford and about 63 miles west of Oklahoma City.

Air Evac Lifeteam operates more than 150 helicopter air ambulances from bases in 18 states, according to the company’s website, which said crews consists of a pilot, a flight nurse and a flight paramedic.