The four schools are Pibul Prachasan, Samsen Nok (Pracharat Anukul), Wichutis and Wichakorn.
Isaramet Kachanukul, Din Daeng district chief, said three of the schools were run by the Bangkok Metropolitan Administration. They were closed for the students' safety.
Tear gas fired by police during the clash was also blown by wind towards Pibul Prachasan, a public school which has over a thousand students. Parents were quickly advised to take their children home.
The schools will remain closed on Thursday and Friday.