Four Missionaries of Charity and 10 to 12 other people were killed March 4 after uniformed gunmen entered a home the sisters operate for the elderly and disabled in Aden, Yemen.
Several news outlets reported 16 people were killed, including patients.
The superior of the Missionaries of Charity at the home survived by hiding, according to the Vatican's Fides news agency. Father Tom Uzhunnalil, an Indian Salesian priest who had been living at the home since Holy Family parish in Aden was sacked and burned in September, was missing after the attack.
Yemen has been experiencing a political crisis since 2011 and is often described as being in a state of civil war with members of the Shiite and Sunni Muslim communities vying for power; in the midst of the tensions, terrorist groups have been operating in the country, including groups believed to be associated with the so-called Islamic State and al-Qaida.
Although most Christians have fled the country, a handful of Salesian priests and about 20 Missionaries of Charity chose to stay and continue their ministry.
Bishop Paul Hinder, head of the vicariate of Southern Arabia, which includes Yemen, told AsiaNews, a Rome-based missionary news agency, that at 8:30 a.m. March 4, "persons in uniform" broke into the Aden compound, killing the guard and all employees who tried to stop them. "They then reached the sisters and opened fire."
Two of the sisters killed were Rwandan, one was from India and one was from Kenya, the bishop said. Father Uzhunnalil apparently was kidnapped, he added.
"The signal was clear: This has to do with religion," Bishop Hinder said.