At least 57 members of an Islamist sect, including children, have been discovered living underground in the Republic of Tatarstan, according to Russian police.

Many of them have never even seen the sun, authorities said.

The sect members, which includes at least 19 children ages 1 to 17, were freed. They were found August 1 during a police raid performed as part of an ongoing investigation into militant groups in Tatarstan. The bunker, which appeared to be made of decrepit concrete blocks, has multiple levels below ground with tight-quartered cells that have no light, ventilation or heat.

The leader of the sect is reportedly Fayzrahman Satarov, an 83-year-old who pronounced himself a prophet destined to direct a caliphate, according to a report by Russia state TV channel Vesti.

Amid chants of defiance, police detained Satarov and some other members, and they are facing charges.

Russian media reports say his followers lived in isolation, refusing to recognize Russian laws or the authority of mainstream Muslim leaders in Tatastan.

The bunker is located near the city of Kazan in Tatarstan, about 500 miles from Moscow.

Tatarstan is majority Muslim and oil rich.

Shireen T. Hunter is a noted scholar on Islam and Russia, and is the director of the Carnegie Project on Reformist Islam at Georgetown University. She has visited Tatarstan and Kazan several times to do research.

It's important, she said, to keep in mind that little is known about the group and simply because the leader identifies himself as Islamist, there should not be immediate connections drawn between the group and Islam in the area as a whole.

"This could just be some 83-year-old who wants to control people," she said. "This may have nothing at all to do with radical or extreme Islam as we understand it. This man - creating a caliphate? How is he going to do that? This just doesn't seem like the modis operandi of a serious radical cell bent on challenging the government."

Kazan is a pleasant city with coffee and clothing shops, Hunter said.  Some women wear hijabs, others don't. Some women work and other choose not to, she said. In recent years, many people have bought villas and other housing in Kazan.

It's conceivable to her that a group could live underground and go unnoticed for years.

"If I decided to live underground in Washington, D.C., I could do that, and so could other people," she said.

Health worker Tatiana Moroz told CNN that the children are in "satisfactory condition" and that they have been fed. Some were sent to the hospital for care.

"Upon receipt from the building, the children were in satisfactory condition," she said. "The children were all fed, although they were dirty. Upon receiving them, we washed them. They have undergone a full examination - all the Russian specialists have examined them, and taken all the analyses. [Friday] the full analyses will be finished and we will give our final conclusion about the condition of their health."

CNN's Matthew Chance contributed to this report.