As of late Monday, no one had been injured.
Deputies were looking for Byron Boyd, age 39, after receiving a tip that he had cut off his ankle monitor. They found him barricaded inside a shop near a residence on County Road 2900 (Ruins Road).
"We were told that the suspect was armed and had made threats to shoot any law enforcement personnel who came near him," said Sgt. Steve Jackson of the San Juan County Sheriff's Office. "We set up a perimeter and called out SWAT."
Traffic was closed from the 11-mile marker on County Road 2900 to its intersection with U.S. Highway 550 north of Aztec.
Law enforcement said Boyd then began shooting at them from the 30-by-50-foot cinder-block structure.
"While we were getting into position we heard three rounds come from the inside of the shop," Jackson said. "At least one of those rounds, we could tell, was directed towards a member of our SWAT personnel. No one was hit by any of the rounds."
Sheriff's deputies contacted Boyd and began negotiating with him. He fired another shot around 12:45 p.m., but no one was injured.
Deputies could not explain another of Boyd's moves.
"We also know that Boyd has emptied three propane tanks inside the shop that he is in. We are not sure why at this time," Jackson said.
The smell of gas lingered into the evening, but deputies were unsure whether it was caused by Boyd's earlier activities.
Sheriff's office spokeswoman Beth Utley said late Monday that deputes were closing in on Boyd.
"He's not in custody yet," she said. Deputies "have managed to break down the door to the cinder block shop that he is in. They just had to send the mechanical robot in."
Boyd, an Aztec resident, was wanted for a probation violation.