KABUL, Afghanistan — He was a polio patient, for 19 of his 21 years receiving treatment at an orthopedic center in northern Afghanistan run by the International Committee of the Red Cross. The organization’s seven rehabilitation centers around the country are often the last hope for a new leg or arm for the thousands who have lost legs and arms to the long war.

She was an experienced physiotherapist with more than a decade of humanitarian work, on her first mission in the country. Her specialty: the patient work of helping children, men and women with disabilities learn how to walk again.

Shortly after 10 Monday morning, he arrived in a wheelchair, supposedly for another therapy session. Instead he pulled out a Russian pistol and fired one shot.

The physiotherapist was struck in the chest — a fatal wound.

In an emotional statement, the Red Cross identified the therapist as Lorena Enebral Perez, 38, of Spain. She had been in Afghanistan for more than a year, shuttling between the organization’s different centers in the north and west. Now she has become the latest reminder of the risks to aid workers in Afghanistan as the violence in the country intensifies.