After receiving a tip-off on cross-border drug trafficking in early January, police in Fengqing County in the city of Lincang dispatched police officers to investigate the case in the counties of Gengma and Cangyuan in Lincang.
After more than two months of investigation, police captured two suspects in Cangyuan county on March 17, seizing 203 packages of methamphetamine from the interlayers of their electric scooters.
The third suspect was caught at a border inspection station in Gengma county on the same day, with 1,480 packages of methamphetamine seized from his electric scooter and residence.
The last suspect was arrested in the neighboring Guangxi Zhuang Autonomous Region in April, according to the police.
The details of the case were first disclosed on Sunday.
The four suspects have been put under criminal detention. Further investigation is underway.
Yunnan is a major front in China's battle against drug crime, as it borders the Golden Triangle known for its rampant drug production and trafficking.