SNOHOMISH COUNTY, Wash. -- Smoke inhalation killed two women and two girls in the mobile home fire in Snohomish, said the Snohomish County Medical Examiner’s office.

Federal and state agents continue to investigate the scene of Tuesday’s fire to find an exact cause. Fire officials have not yet clarified if the fire is a case of arson, but they are calling it suspicious until they find the cause of the fire.

"It's too early in the investigation to tell if it's arson," said Snohomish Police Chief John Turner on Tuesday.

In earlier reports, Snohomish Fire Deputy Chief Ron Simmons said that an accelerant-sniffing dog detected possible evidence of arson in the charred remains of the mobile home.

Simmons said the women who were killed were sisters. The children were daughters of one of the sisters, he said.

Victims Of Snohomish Fire Sought A Fresh Start

The brothers of the two women identified the victims as Maria Montano Reynaga, 28, and Petra Montano Reynaga, 25.

Maria Reynaga's children were identified as Ashley, 7, and Jarele, 3.

The Reynaga sisters, originally from Jalisco, Mexico, were working at Mexican restaurants in Everett to make ends meet, relatives said.

The fire broke out about 7 a.m. at the home in a mobile home park at 1330 Ave. D, near Snohomish High School, about 25 miles north of Seattle.

Firefighter Chad Waters told The Associated Press the home was fully engulfed in flames when firefighters arrived, three minutes after the fire was reported.

Firefighters found the bodies after knocking down the flames, Simmons said.

"Mobile homes are notorious, especially of that age," Simmons said. "We look at them as large ovens."

The manager of Snohomish Mobile and RV park, David Simpson, told KIRO 7 Eyewitness News that the two women had recently moved into the home.

"It was two sisters and the one sister had two children. They just moved in last Friday," Simpson said. "From (when) I met them, they were very nice people."

Simpson said the sisters had recently purchased the home from a previous owner and that the home had been at the park for several years.

Simmons said a corps of chaplains will speak with firefighters, most of whom have children.