PORTLAND — The Portland Water District is responding to a broken water main on outer Congress Street that is slowing traffic now and could complicate the evening commute.

Michelle Clements, spokeswoman for the district, said the district was notified at 11 a.m. Friday that an eight-inch water main ruptured causing some flooding in the area near Massachusetts Avenue and slowing traffic.

Work crews were on their way but the repairs could take eight to 10 hours, she said. It’s not immediately clear what caused the break in the water line. A 12-inch line in the same area was not affected, she said.