Investigators suspect exhaust fumes from a generator killed an adult and child and sickened two others inside an East Point home Wednesday afternoon.

A relative went to the home on Graywall Street, off Headland Drive, to check on the family and found a 40-year-old man and a 13-year-old boy unresponsive, Lt. Cliff Chandler with the East Point Police Department said.

The relative called 911, but officers arriving at the home were overcome by suspected carbon monoxide, Chandler said. Firefighters were also called to the scene and were able to make entry into the home, where the family of four was found.

Two other children, a 11-year-old boy and a 2-year-old girl, were semi-conscious and transported to the hospital for treatment, Chandler said. Their conditions were not immediately known.

When he couldn’t reach his best friend, Morris Horton decided to drive to his home, he told The Atlanta Journal-Constitution. Horton said when he got to the home, his friend’s roommate told him two family members were unresponsive. Horton went inside the home to look for his friend’s children.

“I took the kids outside,” Horton said. “I had one in my arms dead, the other one half-dead.”

An exact cause of the deaths was not immediately known, but a generator’s exhaust fumes were suspected, investigators said. Police believe the generator was being used to provide electricity and heat to the home.

Carbon monoxide is a colorless, odorless gas found in combustion fumes, according to the Centers for Disease Control and Prevention. An estimated 170 people are killed every year in the United States from carbon monoxide poisoning.