Three people were killed instantly with shots to the head, Yemeni officials said. The gunman then headed to the hospital's pharmacy and shot and wounded the pharmacist, Donald W. Caswell.
The Southern Baptist International Mission Board identified the dead as Koehn, 60, of Arlington, Texas, who had planned to retire next year after 28 years of service; purchasing agent Kathleen A. Gariety, 53, of Wauwatosa, Wis.; and Dr. Martha C. Myers, 57, of Montgomery, Ala.
Caswell, 49, of Levelland, Texas, was shot in the abdomen, and hospital officials said he was in critical condition. His father, 71-year-old D.C. Caswell, said his son was recovering after surgery.
"We just thank the Lord that he is alive," the elder Caswell said from Texas. "He's alert and talking and everything's going to be all right, they're thinking."
The killings are "a crime unacceptable in any religion. This contradicts Islam," said a Jibla woman who gave only her first name, Fatima, and said she used the hospital. "They cared for us and looked after us. I can't even count the number of children they treated and saved."
Mission Board spokesman Larry Cox said the organization was "devastated by this news" of the attack. "We are moving quickly to minister to family members" in Yemen and the United States, he said.
Board president Jerry Rankin said his organization would continue to operate in Yemen as long as the government allows.
Carrying weapons is common in Yemen, where people often take them openly into offices and public buildings. At the Jibla hospital, 125 miles south of the capital, San'a, guns were supposed to be checked at the door and all those entering are supposed to be searched.
"The man brought in a rifle under his coat as if cradling a baby bringing him into the clinic," Rankin told reporters in Richmond.