(CNN) Paula Merrill, a nun with Kentucky-based Sisters of Charity of Nazareth, was a nurse practitioner to residents of one of Mississippi's poorest counties.

"We're the only people that will see them," she once said.

Margaret Held, a member of the School Sisters of St. Francis in Milwaukee, Wisconsin, was living her dream of erasing racism and poverty in the deep South.

On Thursday, the two nuns were found dead in the Mississippi community they quietly served for decades, authorities said.

They were found stabbed in a residence in Durant, north of Jackson, Holmes County Coroner Dexter Howard said.

Authorities are offering a $2,500 reward for information leading to the arrest of their killer.

A blue Toyota Corolla that belonged to one of the victims was found on an abandoned road less than a mile from the home, Assistant Police Chief James Lee said.

The Catholic Diocese of Jackson said the two nuns didn't show up Thursday morning at a clinic they operate in Lexington, about 13 miles away.

Clinic workers called police when the pair didn't arrive, said Maureen Smith, a spokeswoman for the Catholic Diocese of Jackson.

Authorities arrived at their home, saw evidence of a break-in and found their bodies, she said.

"They were sweet, very loving ... easy to get along with," Patricia Wyatt Weatherly, who lived next door to the victims, told CNN affiliate WLBT-TV. "They didn't bother anybody."

Howard said their bodies were sent to the state crime lab for autopsies.

The motive for the killings is unclear, and calling it a "robbery would be premature," said Warren Strain, a Mississippi Department of Public Safety spokesman.

The Rev. Greg Plata of St. Thomas Catholic Church, where the sisters attended Mass, described the nuns as "just good women, women of prayer. They were outgoing, loving, caring."

The sisters were much loved by the doctors and residents in the area, he said. They were the primary caregivers at the clinic, he added.

Many of Plata's 30 or so parishioners mourned the women's passing Thursday night at the church.

"We basically cried and told our stories about them and talked about how important they were to us," he said.

The Sisters of Charity of Nazareth said the community is in prayer.

Sisters of Charity President Susan Gatz said, "We pray in gratitude for the precious lives of Sisters Paula and Margaret ... they served the poor so well. Because we are gospel women, please also pray for the perpetrators."

We pray in gratitude for the precious lives of Sisters Paula and Margaret ... they served the poor so well. — Susan Gatz (@susangatz) August 26, 2016

Merrill, who Plata said he believes was 58, was a nurse practitioner in Mississippi for more than 30 years and had been at the Lexington Medical Clinic since 2010. According to the Sisters of Charity website, the clinic saw 8,000 patients in 2014, many poor and uninsured.

Held, 68, was also a nurse practitioner, who moved to Mississippi in 1983. She had been a member of the School Sisters of St. Francis in Milwaukee for 49 years. She moved to Durant in 2003, officials said.

In 2011 she told the School Sisters publication Alive that "a dream and a cause" brought her to Mississippi but that she "stayed because of the people."

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In a video posted on the Sisters of Charity of Nazareth website, Merrill talked about providing health care in a county where the poverty rate is 44%, and the median household income among the 18,000 residents is about $21,400.

"Many people have no health insurance because they can't afford the premiums," she said in the video. "They make minimum wage."

No one else will see them, she said.

The Clarion-Ledger of Jackson reported that Dr. Elias Abboud, the clinic owner, said the sisters raised money to care for the poor.

"They would treat them for free," he said.

The top church official in the area praised their years of working with the poor.

"These sisters have spent years of dedicated service here in Mississippi. They absolutely loved the people in their community," said Bishop Joseph Kopacz of the Jackson diocese.

Mississippi Secretary of State Delbert Hosemann said the sisters had made the community a better place and lamented their deaths.

"Unbridled love and care for mankind has been met with unparalleled savagery," he said.