Hundreds of suburbanites living near a nuclear plant north of New York City were given pills Saturday that could protect them from thyroid cancer in the event of a nuclear catastrophe.

Westchester County residents living within 10 miles of the Indian Point nuclear power station lined up for 130-milligram tablets of potassium iodide. They are meant to be taken if there is a major release of radiation, a possibility that has been taken more seriously since the Sept. 11 terrorist attacks.

"Before Sept. 11, I felt safe," said Jalery Arce, of Cortlandt Manor. "I moved here from the Bronx with my son to be safe. Now I'm getting medicine in case there's a nuclear disaster. I don't feel that safe anymore."

In the first hour, 300 people picked up 1,200 pills outside a high school, said Tony Sutton, deputy commissioner of emergency management for Westchester County, where the Indian Point nuclear complex is located.

Children in soccer gear accompanied parents in golf visors and neighbors gossiped in small groups as demonstrators urged them not to be satisfied with potassium iodide, also known by its chemical symbol KI.

"The only real solution is to close the plant if you want to protect yourself and your children," said Gary Shaw, of Croton, who carried a sign that said, "KI is not an answer."

Since the Sept. 11 terrorist attacks, the government has increased security at all nuclear power plants, taking into account for the first time a possible suicide attack by a large aircraft.

The Nuclear Regulatory Commission began offering the pills to residents within 10 miles of nuclear plants, and 13 states have accepted them. Vermont and Maryland were the first to distribute them, starting in April; New York became the third Saturday.

Potassium iodide combats thyroid cancer, a common result of radiation exposure, by flooding the thyroid glands with harmless iodine and preventing radioactive iodine from getting in. It does not protect against other radiation effects.

Since the terrorist attacks, the pills have been a hot local item. Thousands have been sold over the Internet.