John Spierling, 50, was in good condition and David Krause, 31, was in fair condition Monday afternoon at St. Patrick's Hospital, a hospital spokeswoman said.

Missoula County Sheriff's Sgt. Dave Ball, who heads the local search and rescue team, said both men had fractured kneecaps. Ball said Spierling was scheduled to undergo surgery Monday.

Krause also suffered facial injuries in the incident, Ball said.

The two other men involved in the accident, Kim Sayler, 46, and Ronald D. Berry, 29, were treated Sunday and released. Ball said Sayler suffered a fractured leg and lacerations to his legs. He said Berry received facial and leg lacerations.

Ball said the four men were in a 19-foot Custom Weld river jet boat in the Clark Fork participating in a weekly river rescue training exercise when the accident occurred about 11 a.m.

"We're still investigating, but what we know is the boat was operating downstream when it got into some trouble at the bridge," Ball said. Berry was driving the boat when the accident took place.

Ball said logs and other debris were in the water under a temporary construction bridge on the west side of Orange Street. Ball said he had cleared a passage for the boat under the bridge moments before the accident occurred.

"They started down the wrong passage," Ball said. "They attempted to make a correction at the last minute, but there wasn't enough room to get it done. They clipped a metal beam underwater that they couldn't see."

Ball said the metal beam punctured the boat, which was traveling about 25 mph and stopped it dead in the water.

The men in the boat were thrown forward, then hit by an 850-pound inboard motor that broke loose and slammed forward after the impact.

"The damage to the people wasn't from banging the beam. It happened when the motor broke loose and came forward and whacked them," Ball said.

Spierling was thrown from the boat in the swiftest part of the river, Ball said. He said he helped guide Spierling to shore, downstream from the bridge, before returning to tend to the other three men who were clinging to supports under the bridge.

Krause, Sayler and Berry eventually were rescued by a Missoula City Fire Department boat. Ball said the four men wore life jackets and helmets. Two wore dry suits.

Ball said the $30,000 search and rescue boat was damaged in the collision.

"It's a tossup whether it will be a write-off or not," Ball said. "The visible damage doesn't look that extensive. But it may have structural problems."

Ball said Spierling, Sayler and Krause were veteran search and rescue team members. Spierling, a Missoula dentist, was the senior member of the group with 20 years of service. Ball said Berry was a new member of the team, but had previous experience with the U.S. Coast Guard.