GUANGZHOU - Four passengers were slightly injured in a stampede on a Guangzhou subway train after two male teenagers sprayed irritant gas into the crowd on Tuesday morning, local police said.

The incident happened at 10:48 am on a train of subway Line 5 running from Jiaokou station to Xicun station, according to a statement issued by the local Public Security Bureau through their account on Sina Weibo, the Chinese Twitter-like microblog service.

Preliminary investigation showed that the irritant gas was pepper spray.

The two teenagers fled the scene and further investigation is under way.