The lives of five people in a four-apartment house were endangered early Wednesday when somebody poured gasoline on the floor in a vacant section of the East Main Street structure, according to the Watertown fire and police departments.

City firefighters responded to a 6:25 a.m. suspicious odor complaint at 260 E. Main St., and found that gas had passed through flooring in a first-floor apartment into the basement.

The resident of the adjacent first-level apartment, Linda Pitts, 39, was taken to Samaritan Medical Center for treatment of a headache, a fire department spokesman said.

Lt. Frank J. Derrigo, city police, said an investigation is underway. He declined to say if a means of forced entry to the apartment was found, or if there are leads.

The city codes enforcement office condemned the house, owned by Lawrence Danza, 115 S. Pleasant St., until the property is cleaned and deemed safe.

An American Red Cross volunteer assisted in locating temporary shelter for Ms. Pitts and the upstairs tenants: Lorie Gair, 37, with a 6-year-old girl, and Stephanie Stevens, 33, with a 16- year-old girl.

The Department of Environmental Conservation also responded to the scene, and Egan Excavating, Rome, was retained to do the cleanup.