Delta Township, MI – DELTA TWP. – Two people were rushed to the hospital after being exposed to carbon monoxide early this morning at a local apartment complex, fire officials said.

One person fell and the other had difficulty breathing in the 5 a.m. incident at Westbury Lake Apartments in the 1100 Block of Westbury Drive, Delta Township Fire Inspector Michael Roberts said in a press release. One resident is in stable condition and the other was treated and released from a local hospital, he said. Another resident was treated on scene.

It’s unclear what caused the leak, but common sources are malfunctioning furnaces, water heaters and generators, Roberts said.

Crews discovered 144 parts-per-million of carbon monoxide in multiple units in the same building, Roberts said. Carbon monoxide becomes toxic at 50 parts-per-million, according to the Occupational Health and Safety Association.

Eight of the building’s 16 units were evacuated, he said. Most of the residents have been cleared to return to their apartments.

Roberts said there were no carbon monoxide alarms in the units.

Grand Ledge Area and Lansing Township fire departments also responded to the scene.