SOUTH SIOUX CITY -- Officials are trying to figure out how a car ended up in the Missouri River.

The Nebraska Game and Parks Commission on Wednesday used a boat equipped with sonar to search for a vehicle that's believed to have gone into the river near Fourth Avenue.

A homeowner on Tuesday discovered tire tracks leading to the waterway and a license plate registered to a Pontiac sedan was found nearby, police said. A city video camera also captured images of a car bobbing in the river around 12:35 a.m. Saturday, officials said.

Police are piecing together what happened.

"We've got a vehicle in the water and the exact circumstances are not known to us," said South Sioux City police Chief Scot Ford.

Police have spoken to the car's registered owner, a Minnesota man, but police would not elaborate about what he said. Police don't think the man was inside the vehicle or that it was stolen. They're not releasing his name.

Anyone with information is asked to call police at 712-494-7555.

-- Molly Montag

CORRECTION: An earlier version of this story had the incorrect agency that was searching for the vehicle. It has been corrected in this version.