The North Carolina hotel room where an elderly couple died in April and a young boy died on Saturday had high levels of carbon monoxide, police said today.

Police in Boone called state emergency management and public health officials to the Best Western hotel after 11-year-old Jeffrey Lee Williams died this weekend. His mother, Jeannie, who was staying in the hotel room with him, was taken to the hospital, treated and released.

Police immediately tested the room for carbon monoxide and ordered toxicology tests on the body of Jeffrey and on tissue samples from the elderly couple who died in the same hotel room in April.

"During the emergency medical response, a presumptive test indicated an elevated level of carbon monoxide in the room," Sgt. Shane Robbins said in a statement.

The hotel was evacuated and authorities conducted testing in the room as part of their investigation, he said.

An autopsy performed on Jeffrey Williams determined that he'd died of asphyxiation, while toxicology results from the deaths of Shirley Jenkins, 72, and Daryl Jenkins, 73, showed carbon monoxide toxicity was the cause of their deaths. The couple died on April 16, 2013, in the same hotel room as Jeffrey Williams.

The hotel is now closed as police continue their investigation, Robbins said.