MONTROSE, Pa. -- Yoko Ono, Sean Lennon and Susan Sarandon spoke out against fracking Thursday during a tour of natural-gas drilling sites in northeastern Pennsylvania, warning about what they view as the danger to air, water and human health.

The celebrities boarded a tour bus in New York City and headed to rural Susquehanna County to see gas wells, compressor stations and other evidence of the Marcellus Shale drilling boom, and to visit with residents who say they have been negatively impacted by drilling.

Tom Shepstone of Energy In Depth, an industry group, trailed the sleek silver Mercedes tour bus -- which had trouble negotiating an icy hill at one point and had to creep back down -- and declared the celebrity visit to be a publicity stunt.

"They don't pay mortgages here, they don't have to get jobs here, they don't have to pay taxes here, they don't have to support their families here. They just come up here to pick on this area and use it as part of their trendy cause," he said.

The group: Ono and her son formed a group called "Artists Against Fracking" to oppose drilling in New York state, where they own a farm and where drilling and hydraulic fracturing have been on hold for several years while officials there develop regulations for the industry. Local anti-drilling activists led Thursday's tour in Pennsylvania, where thousands of wells have been drilled and fracked in recent years.

At one well pad, Lennon guided his 79-year-old mother over mud and ice so they could get a better look.

"We hope that what's happened here will be a lesson for New Yorkers," he said. "I hope that New Yorkers will learn from this and tell Gov. (Andrew) Cuomo that it's not something we have to do."

Ono accused the gas industry of disregarding residents' welfare. "They care about making money," she said.

Drillers use the fracking technique to stimulate oil and gas production. It involves the high-pressure injection of millions of gallons of water, along with sand and chemical additives, deep underground to break apart shale rock and free the gas trapped inside it.

The industry and many federal and state officials say fracking is safe when done properly, but environmental groups and some scientists contend the risk of contamination is too great.

One family: The stars met with Matthew and Tammy Manning, who blame the high level of methane in their well water on a natural gas driller, WPX Energy. The driller is paying to deliver replacement water while state environmental officials investigate the cause.

"They say it's safe, but it's not," Matthew Manning told Ono, Lennon and Sarandon. "When there are problems, nobody wants to admit it."

After listening to the couple's story, Sarandon said, "If it's been decided that these people are expendable, and that the people in this area are expendable, there's nothing to stop (the industry) from thinking that they can sacrifice other people in other places. ... It's horrifying and very sad."

Industry officials say the methane in the Mannings' water is naturally occurring shallow gas -- not production gas from the Marcellus formation -- and contend their well was flooded and suffered mechanical failure.