Fontana police Sgt. Billy Green says 46-year-old Lan Randy Hoan was arrested shortly after the Sunday evening shooting at the El Pescado Fish Market.
The gunman repeatedly shot the married couple who own the fish market. Green says their names are being withheld.
They were taken to a hospital where the woman died. Her husband is expected to survive.
The San Bernardino County Sun (http://bit.ly/yezKT8 ) first reported the shootings.
The sergeant says Hoan was apparently involved in a dispute with the owners, but details about a motive haven't been disclosed.
Hoan has been booked for investigation of murder and attempted murder.
