Four policemen were among the seven people injured during the crackdown on student-led protesters rallying in Bangkok on Friday, the Erawan Centre of the Bangkok Metropolitan Administration said on Saturday.
The injured police personnel were sent to Police General Hospital in Bangkok, while other people were treated in government and private hospitals.
On Friday evening, police used water cannons to clear pro-democracy protesters from their rally site at the Pathumwan intersection.
A substance that causes irritation to the eyes and skin if exposed to it was reportedly mixed with the water. Police denied using tear gas but confirmed that the water contained a chemical that could cause discomfort to the skin, which could be washed off with water.