“The sample that they were able to retrieve from the scene may have been diluted by the rainwater,” Lt. Patrick McMahon said.

According to an earlier statement released by the Police Department, officers responded to a call at about 9:40 p.m. last night from a Post Road residence. The caller said she backed over a glass container that was in her driveway and had been exposed to an unknown substance.

Patrolman Philip Gingerella and his brother Peter Gingerella, a reserve police officer, “were both overcome by low lying toxic fumes coming from the property,” according to a statement released by the police.

The 4700 block of Old Post Road was closed until about midnight while HazMat Teams from the state and the Hope Valley Fire Department joined the state Department of Environmental Management in the investigation.

The two officers, the caller, and a friend of hers who had been exposed to the substance were taken to a decontamination area, and then to South County Hospital. In addition to the effects of the substance, they were treated for hypothermia, according to the statement.

Because of “the suspicious nature of the glass container and its contents,” the state Fire Marshal’s Office is also assisting the investigation.