A 51-year-old man armed with a handgun was shot and killed by Yellowstone County sheriff's deputies in an altercation outside the home of the man's son, authorities said Tuesday. The man, whose name was not immediately released, died Monday night. Authorities said the man fired at least two shots at the deputies before they returned fire. The deputies were not injured. An autopsy was planned Tuesday, and the deputies were placed on routine administrative leave pending the outcome of an investigation. Authorities said the man had been living at his son's trailer home until recently, when the two had a falling out. At about 7:30 p.m. Monday, the man showed up at the home with a handgun, Undersheriff Jay Bell said. After the son's wife called police, the two deputies arrived and found the man inside his parked car in front of the home. As deputies approached the car, they called for the man to drop his weapon, Bell said. The man did not respond and began firing, Bell said. The deputies appeared to have acted appropriately, according to Bell. "So far everything looks justified," he said. The names of the deputies were being withheld. The investigation was expected to be completed by the end of the week, Bell said.