According to media reports, two Catholic nuns were found dead in the Mississippi medical clinic where they worked on Thursday, with authorities treating it as a murder investigation.

Sister Paula Merrill, a nurse practitioner with the Sisters of Charity of Nazareth in Kentucky, and Sister Margaret Held, a nurse practitioner with the School Sisters of St. Francis in Milwaukee, worked with the clinic in their ministry with the poor.

The Jackson Clarion-Ledger quoted Father Greg Plata, who worked with the sisters in their clinic in Durant, a small town in western Mississippi, as saying, “These were the two sweetest sisters you could imagine … It’s so senseless.”

Local Church officials said the nuns distributed books, school supplies and other items to the needy.

Although police have not yet formally assigned a motive for the murders, one report suggested that robbery may be the likely cause. The Associated Press reported that although police have not identified a cause of death, it appears the two women were not shot.

The bodies of the two sisters have been transported to the State Crime Lab, where pathologists are expected to conduct autopsies. Both Durant police and the Mississippi Bureau of Investigation are said to be investigating.

Warren Strain, a spokesman for the Mississippi Bureau of Investigation, said a co-worker came to check on the nuns at 10:30 a.m. Thursday, discovered their bodies and contacted police.