Witnesses described the screams of patients echoing through the corridors, with one nun surviving the carnage after hiding in a storeroom fridge when a guard told her to run.
The senseless killings prompted an angry response from Pope Francis, who called for an end to the ten-month conflict in Yemen, which has allowed terrorist groups such as ISIS and al-Qaeda to flourish.
More than 6,200 people have been killed in the conflict, half of them civilians.
A Christian group based in South Africa had reported that the priest now faced death by crucifixion over Easter – one of Christianity’s holiest celebrations.
The Franciscan Sisters of Siessen posted on Facebook: “Was informed that the Salesian priest, Fr.Tom who was kidnapped by ISIS from the Missionaries of Charity Home in Yemen is being tortured and is going to be crucified on Good Friday.
“This calls for serious concerted prayers from all of us.”