At about 1:45 p.m., crews responded to the bayou near San Felipe and Voss Street.
Village Fire Department Interim Chief Howard Miller said someone reported seeing a person waving and splashing in the water before calling 911.
Houston and Village units are checking the bayou from South Piney Point to downtown.
Miller said they have boats, helicopters, and drones checking the banks.
"The water is moving pretty quickly - swollen from the rains. So, that's creating a problem in itself," Miller said, adding that they will search the area "as long as it takes."
A description for the person reportedly seen in the water was not given.