The young men, all 18, were in a barn at the Raymond and Mae Buelow farm Tuesday evening when there was an explosion, said Capt. Brian Gardner of the Linn County sheriff's office.
The Buelows' grandson, Tyler Wayne Buelow, of Palo, and Grant Stephen Rutherford, of Cedar Rapids were pronounced dead at the scene.
The third person, Ryan Phillip Rezin, of Cedar Rapids, was in critical condition Wednesday at University Hospitals in Iowa City, Gardner said.
Gardner said the cause of the blast was under investigation.
He said it was caused by some sort of device. It was not drug related and not caused by natural gas, he said.
The blast originated in a partitioned room in the barn, he said.
Gardner declined further comment on what caused the explosion.
The victims suffered multiple injuries, including burns, Gardner said.
Autopsies were being performed on Buelow and Rutherford Wednesday at Mercy Medical Center in Cedar Rapids.
The victims were removed from the barn by rescuers, Gardner said.
Authorities received a call about 9:30 p.m. Tuesday from a neighbor who reported hearing an explosion.
Gardner said no fire was visible when rescuers arrived. Windows in the barn had been blown out but otherwise the building was structurally sound, he said.
A neighbor, Erin Kelly, 22, said she heard a noise similar to a car backfiring about 10 minutes before police arrived. She said she looked outside but didn't see anything.
The state fire marshal's office was assisting in the investigation.
