Police said they believed the same bullet may have killed Suresh Barwa, who was from India, and Marco Laspuna, from the Philippines.
Barwa died on the spot at the Missionaries of the Poor kitchen on Thursday night while Laspuna died in hospital four hours later.
The incident happened about 9 p.m. in the missionary group’s Corpus Christi premises in the crime-riddled downtown district of Kingston. Jamaica has one of the highest murder rates in the world.
Father Richard HoLung, head of the Roman Catholic missionary, told reporters: "We had just finished having supper and five brothers were in the kitchen washing dishes when a bullet went through the brother’s head."
HoLung said none of the missionaries had an idea where the bullets came from.
Jamaica’s National Security Minister, Peter Phillips, who toured the mission on Friday, gave his assurance that the police would do all they could to bring the killers to justice.
The Missionaries of the Poor care for more than 500 homeless and destitute people at five centers in downtown Kingston. More than 1,000 people receive clothes, food and medical care from the Jesuit priests each day.