WARREN — A state fire marshal’s investigation into the fatal New Year’s house fire that killed a Warren mother and her son indicates the origin of the blaze possibly was a plastic tote on the back patio that held cigarette ashes from a party that ended just hours before.

The investigation by assistant state Fire Marshal Todd Stitt officially shows the cause of the fatal blaze at 2853 Woodland St. NE to be undetermined.

“Based on my education, training and experience along with the physical evidence examination and statements … the cause of this fire is being ruled as undetermined,” Stitt wrote in his report.

The fire killed Cassandra Gray, 34, and her 5-year-old son Otto Gray, who died at the scene from smoke inhalation, according to a report from the Trumbull County Coroner’s Office.

According to the incident report, Lee Gray, 43, told investigators he was sleeping in the living room and was awakened by the smoke. The report showed that Warren firefighters received the call for the structure fire about 3:15 a.m.

Lee Gray said his younger son Simon was sleeping in the living room with him. Lee Gray opened the door to a rear sunroom and observed a wicker toy chest on fire next to the window. Gray said he then went to the second floor to alert his wife, who was sleeping in a bedroom with their other son.

Gray told investigators he went back downstairs to get a fire extinguisher. He opened the door to the sunroom to try to put out the blaze and the fire extinguisher failed, he told investigators. The room was fully involved with fire.

Then Gray took his son Simon and exited the house through the garage.

Warren firefighters knocked down the flames on the second floor and found the woman and her child dead in a bed in the northwest bedroom.

The sunroom’s exterior wall was consumed by fire and investigators found a wood pile on the patio with fire damage.

“The roof of the structure was consumed by fire and / or collapsed into the second floor of the structure,” Stitt wrote.

An investigation of the patio found melted to the wood floor was the base of a blue plastic tote, with the wood flooring around the tote consumed by fire. An interview with Lee Gray revealed that ashes from the fireplace were in the blue tote as well as cigarette butts from guests at a New Year’s Eve party earlier in the evening.

“Examination of the wood decking showed a large portion of the decking consumed near and around the tote,” Stitt wrote.

Stitt noted the case will remain open pending the complete autopsy report and further video data collected.