Investigators still have not established a motive in the shootings of two brothers by a man who then crashed his van into the sheriff's office and was killed in an exchange of gunfire with lawmen.

"We're working on some motives and should have a statement Monday on what we assume the motive is," Uinta County Undersheriff Dwain Booth said Sunday. "There are two or three avenues that we're considering."Phillip Mensing, 45, Evanston, was dead on arrival at an Evanston hospital after the Saturday shooting. An autopsy indicated Mensing died of a bullet wound to the liver.

His brother, Steven Mensing, 43, was shot in the abdomen. Booth said Steven Mensing's wound was "life-threatening." But a nursing supervisor at IHC Evanston Regional Hospital said Monday morning that he was in critical but stable condition.

The suspect, Kenneth Stefanick, 49, Evanston, died of gunshot wounds to the head.

The shooting began about 5 p.m. Saturday at a landfill dump, where the brothers had taken a load of trash.

Booth said landfill workers telephoned police, and officers were en route to the dump when they spotted Stefanick driving back toward town. Two cruisers turned around and chased the suspect into Evanston, where he crashed into a brick wall at the sheriff's office.

Police Sgt. Dave Furlong said Stefanick got out of his van and fired two or three shots at officers. They returned fire, striking the man in the head.

The gunman was taken to Evanston Regional Hospital, but was transferred by helicopter to the University of Utah Hospital in Salt Lake City. He died at 8:17 p.m., about three hours after the shooting.

Furlong said Steven Mensing and Stefanick lived across the alley from each other.

"We don't know why he (Stefanick) was out there unless he was there to have a confrontation with him (Mensing)," Furlong said.

There were no injuries when Stefanick's van crashed into the sheriff's office. But Booth said the squad room area and the report area were destroyed, and damage was estimated at $10,000 to $20,000.