Several people who work or live near the hospital, including two nuns, were missing in the wake of the attack.
The DRC ranks at number 40 on the 2021 Open Doors World Watch List for Christian persecution.
The civilians were taken hostage during a skirmish with the Congolese army.
Both South Sudan and the DRC continue to suffer from internal unrest, which has caused the displacement of millions.
Reportedly, the relationship between the Catholic Church and Congolese government has been tense for many years.
For years, dozens of armed militias have wreaked havoc in the DRC, a predominately Christian nation.