Scott County authorities spent much of Labor Day Monday searching the Minnesota River near Belle Plaine where an unoccupied boat with its motor running was found on the riverbank.

Sheriff's deputies were called to the Hwy. 25 bridge just north of the far southwest metro city's downtown area after witnesses spotted the unmanned watercraft about 10:50 a.m., according to a statement from the Scott County Sheriff's Office.

Responders from several agencies walked the shoreline and searched the river in an attempt to find anybody who may have been in the boat. As of 5 p.m., no one had been found, the sheriff's office said.

"The search will continue into the evening until darkness makes it unsafe for responders to be on the river," the sheriff's office said.

Search operations will resume on Tuesday, if necessary, the statement said.

Tim Harlow