BEIJING (AP) _ The latest weapon in the fight against cheating for China’s all-important college entrance exam is a six-propeller drone.

It flew over two testing centers in Luoyang city in central China’s Henan province to scan for any unusual signals being sent to devices smuggled by students taking the annual test.

A Henan province news website says no such signals were detected Sunday, the first day of test. Almost all Chinese high school graduates must take the test, and their scores are the key criterion for which tier of university they can enter.

Luoyang’s Radio Supervision and Regulation Bureau says the drone cost hundreds of thousands of yuan (tens of thousands of dollars).