Authorities responded Tuesday morning to a call for carbon monoxide poisoning.

A neighbor called 911 around 9 a.m. Tuesday after a mother and two children were found unconscious at their home on Trails End North off of Flanders Filters Road in Washington, according to Washington Fire-Rescue-EMS Battalion Chief Doug Bissette.

The incident is still under investigation. Bissette said there were multiple gas heaters in the home, which are potential sources of carbon monoxide. All three victims were transported to Vidant Beaufort Hospital.

Their names are not being released at this time.

Bissette said carbon monoxide concentrations in the home measured 250 parts per million when first responders arrived — a deadly amount. A normal concentration of the odorless gas would be around 25 ppm.

According to Bissette, Washington first responders had only ever seen a concentration up to 70 ppm until Tuesday’s incident.

About 1,500 Americans die each year from carbon monoxide poisoning; 900 of those deaths occur in homes, according to data from the Centers for Disease Control.

Carbon monoxide begins to affect human health at only a few parts per million.

There is no word at this time on the victims’ conditions, but Bissette said first responders were hopeful all would recover.