HOBART | A 55-year-old woman living in a group home for people with development disabilities died of carbon monoxide poisoning Saturday morning, and six other people were sent to the hospital for treatment or examination.

Toby Sandilla died at the scene at 420 Crestwood Drive. The home's other four residents and two police officers who responded to the scene were treated at hospitals in Lake and Porter counties. Their conditions were not available Saturday night.

"It's a terrible accident," said Kris Prohl, executive director of ArcBRIDGES of Gary, the nonprofit organization that operates the home. "All the people who know the (victims) are devastated."

Prohl said the home was equipped with a carbon monoxide detector and that an investigation will determine whether it was working properly.

"Our intent is to provide the safest care and treatment that out clients can receive," Prohl said.

ArcBRIDGES workers who came to the home about 8:30 a.m. Saturday discovered they could not enter. A neighbor who saw the workers looking into windows called police about 8:40 a.m.

"They were employees, and they were locked out," neighbor Susan Branley said. "When they got inside, all the windows were thrown open right away."

Another neighbor, Glen Lederman, said carbon monoxide concentration in the home must have been severe, because the two police officers who were hospitalized were inside for less than 10 minutes.

A Hobart police news release said all five occupants of the home were unconscious or sleeping when authorities arrived because of "extremely high levels of carbon monoxide."

The Lake County coroner's office has not officially ruled Sandilla's death was from carbon monoxide poisoning because an autopsy and toxicology tests were pending.

ArcBRIDGES, which was formerly known as the Lake County Association for the Retarded, operates 29 state-licensed homes in the area to assist people who have development disabilities with daily living, Prohl said.

Neighbors said they rarely saw the occupants of the home except when they boarded a daily bus to take them to their jobs.

"They were very nice people. You never had any problems with them," neighbor Jen Lederman said.

It was not clear why carbon monoxide filled the home. Experts say carbon monoxide often comes from an improperly operating furnace, water heater or stove, although any gas-burning appliance can emit the odorless, colorless gas.

Low levels of carbon monoxide can cause flu-like symptoms, including headaches, nausea and drowsiness. The chemical is dangerous because it basically bonds to a body's hemoglobin, which prevents oxygen from getting into the bloodstream.