MINNEAPOLIS, Minn.—The 12 year-old west-central Minnesota boy injured in a grain silo accident last weekend has passed away.

A post on Alex Boesl’s CaringBridge page says the young boy died Thursday from his injuries.

Alex had been hospitalized at Children’s Hospital in Minneapolis for the past week, after he inhaled toxic fumes in a silo near Millerville, Minnesota, on December 21st.

Millerville is located northwest of Alexandria, in Douglas County. 

Alex’s father Curt Boesl, and Curt’s brother Steve Boesl, also died from their injuries.

Authorities have not said specifically what happened in the silo, although fermentation of silage can form a variety of gases, including highly toxic nitrogen dioxide.