"There was one hit," Hansen confirmed.
The sweep took place on Thursday, May 17, at about 10:30 a.m. and lasted about a half hour, he said. It focused on a parking lot, and not gym lockers, which are also permitted under school district policy.
A drug detection dog alerted to a car; no drugs were found, according to a police report, which said a search of the car turned up a knife.
A 16-year-old male was arrested for possession of a knife on school grounds. His name has been withheld because he is a juvenile.
Hansen, who said the aim of the sweeps is school safety, called it a success, although one aspect -- doing the sweeps without being seen by students -- didn't work out.
"We tried to do it at a time when the kids are in class, but of course, there's one building with a window that faces the parking lot," he said.
Hansen said because of that, news of the search spread though the school.
No one was arrested in the first search, which took place at Foothill High on Friday, May 4, during third period.
That search, which took about an hour, also focused on a parking lot and turned up two pipes hidden in bushes at the school.
District policy allows for the searches as long as the dogs do not interact directly with the students.