A dog left alone in a truck Sunday afternoon died after the idling vehicle rolled or powered into the Kenai River, according to the local police department.

Kenai Police Sgt. Paul Cushman said the dog's owners told police that they believed the dog shifted the truck into Drive or Neutral. The truck had been parked on the south beach near the river's mouth, Cushman said in an interview Tuesday.

"It was reported that the vehicle was running during the incident," he said in an email. The interlock that prevented the truck from shifting out of Park into an active gear without applying the brake wasn't working, Cushman said.

"The owner believes the vehicle was in Park and that the dog caused it to go into gear," Cushman said. "He reported that his vehicle could do so without pressing the brake."

Cushman said police got a 911 call at 1:55 p.m. Sunday reporting that the truck had rolled into the river.

"We responded and located a couple there that said their truck had accidentally been bumped by their dog that was inside," Cushman said. "At least that's what they believe happened."

Cushman said he was not one of the officers who responded to the call, but believed the truck "was completely submerged when it went into the water." Curt Wagoner, Kenai city streets foreman, said the truck had rolled down "kind of a steep bank." Kenai Fire Chief Jeff Tucker described the sand in the area as hard-packed.

Cushman said the couple who owned the dog had been in the area "enjoying the view." He declined to provide their names.

The Peninsula Clarion first reported Monday that an unaccompanied dog had shifted a white 2005 Dodge Ram pickup into neutral, sending it into the Kenai River. The "Dipnet Kenai" smartphone app later alerted users to a "potential navigational hazard" in the river on Monday, the newspaper reported.

Monday was the first day the Kenai River dipnet fishery opened. With the opening of the personal-use fishery, people and boats were expected to crowd the river, primarily to catch sockeye salmon over the next three weeks.

Cushman said officials with several agencies, including the Kenai Fire Department and Central Emergency Services, assisted in removing the truck on Monday.

"We went out there because it was a hazard to navigation," said Tucker, the Kenai fire chief.

Tucker said divers hooked a 100-foot tow strap to the truck during low tide. Two front-end loaders then hauled it out of the river.

"The dog did not get out," Cushman said. "So the people are pretty distraught over that."