A dozen family members were returning home from a hunting trip in South Dakota when their small plane, flying in blizzard-like conditions, crashed shortly after takeoff on Saturday. Nine people, including two children, were killed, the authorities said.

Jim Hansen and Kirk Hansen, brothers and founders of Kyäni, a health and wellness company, died in the crash, according to a statement posted by Travis Garza, the company’s president.

The two men were also executives with Conrad & Bischoff, a family-owned petroleum business, and KJ’s Super Stores, a chain of gas stations, carwashes and convenience stores in Idaho, Nevada, Utah and Wyoming.

Members of four generations of the family died, according to the statement.

The victims included Jim Hansen and Kirk Hansen’s father, James. Also killed were Kirk Hansen’s sons Stockton and Logan; and Kyle Taylor and Tyson Dennert, his sons-in-law.