Three Americans were killed on Thursday when a security guard opened fire at a Kabul hospital funded by a US Christian charity.
They included a doctor and a father and son visiting the hospital. A fourth American was wounded, the Health Ministry said.
The security guard shot himself after the attack and was treated at the hospital before being transferred to Afghan custody.
The shooting occurred in the grounds of the Cure Hospital, which specialises in children's and maternal health.
The Cure organisation began operating the hospital in 2005, at the invitation of the Afghan government, and 27 doctors and 64 nurses work there, according to Cure's website.
The Taliban has claimed responsibility for similar attacks this year, but made no comment about this shooting.