Armed men kidnapped an American missionary from a school in Nigeria and have demanded the equivalent of almost $300,000 for her safe return, Nigerian police said Tuesday. The Rev. Phyllis Sortor, a missionary with the Free Methodist Church in Seattle, was identified by her church as the U.S. citizen abducted from the Hope Academy compound in Kogi state.

A group of five armed men, three of whom had masks over their faces, jumped the walls of the compound and fired shots into the air at 10:30 a.m. local time Monday (4:30 a.m. ET), Kogi Police Commissioner Adeyemi Ogunjemilusi said. Speaking to NBC News via telephone, Ogunjemilusi said police believe Sortor was the target of the raid because no one else was taken and there were no injuries. Her captors contacted a friend and demanded 60 million naira (almost $300,000) for her safe return, the commissioner added.

The region of central Nigeria is not a common area of operation for militant group Boko Haram. Ogunjemilusi said he believed the kidnapping was carried out by a criminal gang.

He said security forces are currently sweeping an area of thick forest behind the compound. “We will do all within the available resources to ensure the safe rescue of the victim,” he said.

The Free Methodist Church said in a statement that the U.S. Embassy in Nigeria had been notified and the State Department and FBI were working with local authorities to rescue Sortor. A State Department spokesperson said officials were aware of reports that a U.S. citizen is missing, but declined to release any information because of privacy concerns.

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Free Methodist officials said they were "calling on the U.S. church to join together in prayer for Phyllis’ safety and speedy release."

Sortor is an alum of Seattle Pacific University, a Christian institution, reported NBC affiliate KING5. Her stepson, Richard Sortor, told the station at a prayer service at the school Monday night that she "believes in God, she's doing God's work." He added that the news was "surreal, just surreal. I can't believe this."

The Free Methodist Missionaries’ website describes Sortor as a financial administrator for Hope Academy and an extension school in Ikot Ntuk. In a series of newsletters, she describes the progress of building a new school for ethnic Fulani children — part of a predominantly Muslim group of semi-nomadic herders.

Sortor, a grandmother, had been in the U.S. last fall but recently returned to Nigeria, said Brenda Young, the director of the Ohio-based Clear Blue Global Water Project. The group has financially assisted Sortor in Nigeria, where she had been helping to build wells and bring clean water to her community. "She's a very courageous woman," Young told NBC News. "She’s one of the most devoted, compassionate, hard-driving women I’ve ever known."

Young said Sortor, the daughter of missionaries, had been volunteering in West Africa for more than a decade, including with her late husband, Jim. She never expressed concern about her safety in Nigeria, Young added. "Her feeling was that these were her people, and that she loved them," Young said. "She felt like this is where she was supposed to be."

In a video interview recorded in 2009 with Free Methodist Missionaries, Sortor described how friends — Christian and Muslim — showed kindness and paid the hospital bills when her husband was dying a year earlier in Nigeria. She said she would continue to use her faith to guide her work. "I know that nothing that can happen to me in my future can ever defeat me with God by my side," she said.

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Missionary from Western Washington abducted in Nigeria http://t.co/QqyU1cw66d pic.twitter.com/CFgJPhNIxV — KING 5 News (@KING5Seattle) February 24, 2015

We are joining with the @fmchurchusa and others around the world in praying for SPU alumna Phyllis Sortor. http://t.co/w6FEx4vytt — Seattle Pacific Univ (@SPUnews) February 24, 2015

— Alexander Smith and Erik Ortiz