Four people were treated and released for carbon-monoxide poisoning Saturday after the furnace in their rental home in the 4700 block of South Logan Street in Englewood malfunctioned.

“As soon as I woke up, I had a splitting headache this morning,” David Collins told 9News.

Collins’ fiancee, his two daughters, ages 2 and 5, and his grandmother were all treated at Swedish Medical Center. There was a carbon-monoxide detector in the home, but Collins told reporters the battery turned out to be dead.