About 10 small Westminster businesses were closed temporarily Saturday after raw sewage began flowing from drains into the stores and onto the parking lot, police said.
Merchants said they were forced to close shops at the West Grove shopping center at Westminster Boulevard and Newland Street about 5 p.m. Friday.
County health officials were investigating Saturday.
Westminster Police Lt. Ron Weber said a pipe that linked a restaurant, bakery, laundermat, bar and other stores became clogged and drains overflowed.
Cleaning crews were busy Saturday, and the businesses are expected to reopen today.