HELENA, Mont. -

Authorities say a 4-year-old boy and 3-year-old twins were among the five people killed when their truck collided with a fire engine last week outside of Helena.

Jefferson County Undersheriff Mike Johnson on Monday says the children were 4-year-old Breighton Boegli and 3-year-old twins Peighton (PAY'-ton) Boegli and Madison Boegli.

Johnson identified the adults as 29-year-old Matthew Boegli and 30-year-old Crystal Ross. The family lived in Townsend.

Johnson says it could take weeks to receive the results of autopsies and determine a cause of death.

The family was driving in a pickup truck west on U.S. Highway 12 on Thursday when the truck collided with a fire engine driven by Three Forks Fire Chief Todd Rummel.

Rummel also died in the fiery crash. A memorial service for Rummel has been set for Wednesday.