Screening Machine Indicates Explosives in Bag By PAUL SINGER .c The Associated Press CLEVELAND (May 3) - Two airport concourses were evacuated after a passenger's bag set off an explosives detector, and the passenger and bag disappeared into the crowd before security personnel noticed, authorities said. Airport Commissioner Fred Szabo said screeners were unable to locate the bag in a search of the concourses. He could not rule out the possibility that the passenger got on a departing flight with it before the concourses were closed. The explosives detectors frequently return false readings, Szabo said. But without the bag, he said, there was no way of knowing if Friday's incident was a false alarm. The bag set off the detector at a security checkpoint run by Huntleigh International of St. Louis, but the alarm wasn't immediately noticed, Szabo said. By the time a security worker saw it, the bag and the passenger carrying it were out of sight, he said. Huntleigh officials declined comment Friday. The two concourses at Cleveland Hopkins International Airport and 14 planes at their gates were emptied about 10:30 a.m. because of the security breach, Szabo said. Passengers were allowed back into the concourses to be rescreened shortly after 1 p.m. Last October, two concourses at the airport were closed for 3 1/2 hours when a security device gave what turned out to be a false reading indicating explosives in a carry-on bag. No explosives were found. Leo/ORD