A prominent billboard known for its eye-catching gun-control ads now feature an updated message calling on voters and lawmakers to support a renewed federal ban on assault weapons.

The billboard, 252 feet by 20 feet, hangs above the Massachusetts Turnpike near Fenway Park. Thursday evening, it was transformed to read “Assault weapons have stopping power. Fortunately, so does your vote. We need a Federal Assault Weapons Ban NOW!’’ The second and third sentences are separated by a bloody handprint.