Authorities charged two teenagers in connection with a break-in at a water facility and expected to charge a third as more than 9,000 area residents waited to hear Wednesday if their drinking water had been contaminated.

The teens are suspected of cutting the barbed wire at the facility late Monday, cutting lines to an alarm, and then damaging an electrical panel and a vent at the top of a 1.3-million-gallon water storage tank, said Blackstone Police Lt. Gregory Gilmore.

A 5-gallon container with an odor was found on top of the tank, but authorities do not yet know what, if anything, was put into the water.

Gilmore said the teens became suspects after talking about the incident at school.

"At this point, the police are considering this to be a vandalism incident, not an act of terrorism, but all due diligence should be used until test come back, hopefully negative," he said.

"We know for sure that when they tampered with the vent cover at the top of the tower some debris had fallen into the water supply," Gilmore said.

The two 15-year-old boys, whose names were not released because of their ages, were charged with malicious destruction of property, tampering with a public water supply and polluting the water supply, all felonies, and trespassing, Gilmore said. He said a 15-year-old girl had not been arrested but likely would be charged with trespassing.

The water system serves Blackstone's nearly 9,000 residents and about four dozen homes in neighboring North Smithfield, R.I., about 55 miles south of Boston.

Authorities ruled out terrorism on Tuesday, and the FBI had decided not to pursue the case, said Dr. David Gifford, director of the Rhode Island Health Department.

Still, a water ban was in effect while the water and container were being tested for biological or chemical contaminants, Gifford said. He said the test results were expected Wednesday.

The Blackstone-Millville school district canceled Wednesday classes as a precaution, even though no illnesses had been reported, and residents stocked up on bottled water. School officials on Tuesday had locked the bathrooms, rented portable toilets and provided bottled water for students.

"I'm wondering, `OK, how bad is it?"' said Charlene Gignac, a 40-year-old convenience store clerk who said she had taken a shower. "I still have a pulse and I'm still kicking."

Some residents said authorities should have warned them sooner.

Lori Wadsworth, 40, of Blackstone, said people couldn't help but wonder about terrorism. Even in a small town, feelings have changed since Sept. 11, she said.

"We wouldn't have thought twice about it. We would have thought it was mischievous kids," Wadsworth said. "Now you're wondering `Could it be?' Who would come to Blackstone to terrorize the citizens here?"