The Moorhead police say family members did a welfare check at the residence on Saturday night when they found the bodies of four adults and three children and called 911 just before 8:00 p.m.

Authorities identified the victims as 37-year-old Belin Hernandez, 34-year-old Marleny Pinto, 32-year-old Eldor Hernandez Castillo, 19-year-old Mariela Guzman Pinto, 16-year-old Breylin Hernandez, 7-year-old Mike Hernandez and 5-year-old Marbely Hernandez.

“The preliminary autopsy has ruled out any obvious trauma as the cause of death; however, the blood samples from the victims have been transported to a lab for further investigatory examination, and we do not have any timeline on those results,” Moorhead police said Monday.

Local station KVVR reported that the Noticias Digital of Honduras news service said the family—a mom, dad, three children, an aunt and niece from Honduras—probably died from “gas poisoning,” although an official cause of death has not been given by the Ramsey County Medical Examiner’s office.

According to Inforum News Service, dispatch records indicate that the Moorhead fire department responded to a call to check on a carbon monoxide detector at the victim’s residence around 1:00 a.m., “several hours after the bodies were discovered.”

It was unknown if the house had working carbon monoxide detectors or who placed the call.

Inforum News Service said the children attended Reinertsen Elementary and Moorhead High School. Police said that the Moorhead Area School District has been informed of the children’s death to help prepare to offer help and support for their students, local affiliate Fox 9 reported.

There were no signs of violence or forced entry, police said. Authorities were not seeking suspects.

“This is an absolute horrible tragedy, made even more poignant since it is close to the holidays,” Moorhead Mayor Shelly Carlson said in a statement. “My heart aches for the family and friends who received this devastating news over the weekend. Our community mourns with them during this heartbreaking time.”

The home where the deceased were located is on the 4400 block of 13th Street South in Moorhead, a city located about three and a half hours northwest of the twin cities. Moorhead is on the Minnesota border next to Fargo, North Dakota, in a metropolitan area of about 230,000 people.

The Associated Press contributed to this report.