FBI agents search homes, won't say why

CHESTER, Pennsylvania (CNN) -- About 30 FBI agents, some wearing hazardous materials gear, searched two houses in this town about 13 miles southwest of Philadelphia Tuesday and set up a decontamination tent outside.

FBI spokeswoman Linda Vizi said no one has been arrested and the search warrants are sealed. She said she would be able to give more information if they were unsealed.

When asked if the residents would be allowed back in their houses following the search, she replied, "Probably. Nobody's under arrest. That's all I'm going to tell you."

When asked if there was a threat to the immediate area, she said, "No threat. Everything is contained. Whatever problem it is, it's contained."

The Philadelphia Inquirer reported on its web site that FBI agents were seen going in and out the house with no protective masks or gear, and that agents carried large green plastic bags out of the house.