Hooray! Mexico to the rescue of US!

Bet that's not a sentence you ever thought you'd hear.

A Mexican army convoy began crossing into the United States on Thursday to bring aid to victims of Hurricane Katrina.

Carrying water treatment plants and mobile kitchens that can feed 7,000 people daily, the convoy bound for San Antonio is the first Mexican military unit to operate on U.S. soil since 1846.

The first green tractor-trailers, with Mexican flags attached to the tops of their cabs, crossed the international bridge at Laredo at about 8:15 a.m.

The rest of the 45-vehicle convoy was in a staging area on the U.S. side in about 15 minutes.