LUOYANG, China (CBSDC) — Drones are now being used to stop test cheaters.

The Guardian reports that China is using surveillance drones to spot students cheating on college entrance exams.

The six-propeller drone first began flying over two testing centers on Sunday in Luoyang. The drone was scanning for cheating devices that might have been brought in, such as wireless equipment to communicate with others during the test.

The Guardian reports that there were no such signals during the first day of testing.

“A drone has its advantages. In an urban area full of tall buildings, various barriers limit the operating range of devices on ground, while the drone can rise up to 500 meters and detect signals over the whole city,” Lan Zhigang, Luoyang’s radio supervision and regulation bureau, told The Guardian.

More than 9 million Chinese high school graduates began taking the test on Sunday.

At least 23 people have been arrested since May for trying to cheat on the exams.

In March, a drone was flown onto the White House grounds. No charges were filed against the drone operator.