San Francisco is suing makers of the ultra-processed food that health experts say has led millions of Americans into obesity during decades of over-consumption, the city said Tuesday.

In what officials said was a first-of-a-kind lawsuit, the liberal California city is taking to task some of the largest names in groceries, including Kraft Heinz, Coca-Cola, Nestle and Kellogg.

"These companies created a public health crisis with the engineering and marketing of ultra-processed foods," San Francisco City Attorney David Chiu said.