STANTON, Del. (AP) — Four people were found dead at a homeless camp in Delaware on Tuesday, possibly from carbon monoxide poisoning linked to a heater discovered inside their tent, according to a family member and authorities.

An autopsy will determine the four adults’ causes of death, but no foul play was suspected, Delaware State Police confirmed in a statement Tuesday.

Bruce Messick, who identified himself to the Delaware News Journal as a family member of two of the victims, said he went to check on his brother and nephew that afternoon in the woods off of Route 7 in Stanton, when he found the group dead inside a tent equipped with a propane heater.

Messick said his family members had been homeless for years and he often brought food and money to the them. The almost-full propane tank being used by the four victims to keep warm had recently been dropped off, he added, and temperatures below freezing had been recorded throughout the week.

The victims’ names were not immediately release and State Police were continuing to investigate.