Crews restored service about 9 p.m. Saturday and had the street repaired by 11 p.m.
Patterson blamed the break on "just old age and possibly a small shift," but said there was no way to tell for sure what caused the break.
Patterson said the line broke about 4 p.m. Saturday in front of Square Books and affected businesses around the downtown Square.
Many of the restaurants had low water pressure from the break. Among those closing early were Ajax Diner and Old Venice Pizza.
Ajax Manager Katherine Montague said she closed the restaurant about 6:30 p.m. because she couldn’t run the dishwasher. Old Venice Pizza stopped seating customers about 7 p.m.