Exhaust pipes meant to vent carbon monoxide from the boiler in a Delaware apartment complex where four people were found dead last week had rusted and collapsed, officials said.

The News Journal reported that officials with the Delaware Department of Natural Resources and Environmental Control toured the apartment building Monday and found several items that needed to be replaced.

Alex Rittberg is the department's environmental programs administrator. He said the state of the exhaust system in the building forced wasted gas from the boiler to enter the mechanical room. The mechanical room is directly beneath the two apartments where people died.

Law enforcement officials have said that high levels of carbon monoxide were present, but they haven't yet ruled on the official cause of the residents' death.