At Los Angeles International Airport, TSA screeners have missed 75% of the fake bombs planted to test security.

WASHINGTON — Security screeners at two of the nation’s busiest airports failed to find fake bombs hidden on undercover agents posing as passengers in more than 60% of tests last year, according to a classified report obtained by USA TODAY.

Screeners at Los Angeles International Airport missed about 75% of simulated explosives and bomb parts that Transportation Security Administration testers hid under their clothes or in carry-on bags at checkpoints, the TSA report shows.

At Chicago O’Hare International Airport, screeners missed about 60% of hidden bomb materials that were packed in everyday carry-ons — including toiletry kits, briefcases and CD players. San Francisco International Airport screeners, who work for a private company instead of the TSA, missed about 20% of the bombs, the report shows. The TSA ran about 70 tests at Los Angeles, 75 at Chicago and 145 at San Francisco.

The failure rates at Los Angeles and Chicago stunned security experts.

Meanwhile, at Detroit Metro, screeners in Islamic veils are frisking elderly, wheelchair-bound nuns.