AmberAlert system is not down. At least 2 alerts happened over wkd. DOJ site offers info abt system but alerts get issued by states/counties— Brian Fallon (@brianefallon) October 7, 2013
The federal website, AmberAlert.gov, is temporarily down. But the system itself is still functioning. As the above statement makes clear, Amber alerts are issued by state and local authorities. Those haven't been affected by the shutdown.
UPDATE 10:51 a.m. ET
The federal Amber Alert website seems to be back up.