KLM said Monday it is “deeply saddened” by the death of one of its employees in a plane crash that occurred around 4 p.m. (local time) Sunday near London Southend Airport, according to RTL. All four people on board were killed, including the KLM colleague.

The plane, a Beech B200 Super King Air operated by Zeusch Aviation, crashed shortly after takeoff from the airport. The aircraft had been en route to Lelystad Airport in the Netherlands. Flags at Lelystad Airport were flown at half-mast on Monday.

KLM issued a public statement Monday expressing condolences and support for the victims’ loved ones. “We are deeply saddened by this terrible news. We offer our heartfelt condolences to the families and friends of the victims and ask everyone to respect their privacy,” the airline said. “We naturally stand ready to support the next of kin.”

The aircraft was operated by Zeusch Aviation, a company based in the Netherlands that specializes in medical repatriation flights and aerial survey operations. According to Sky News, the crash killed two crew members—a Dutch pilot and co-pilot—and two passengers: a nurse from Chile and a doctor from unnamed European country.

Among the victims was 31-year-old Maria Fernanda Rojaz Ortiz, who was working her first shift as a flight nurse at the time of the crash. Friends described her to the BBC as “the kindest soul” and someone who “didn’t have a single bad bone in her body.” They said she chose a nursing career because it reflected her selfless nature.