Police were called to the scene of a school north of Bangkok on Friday due to an alleged gunman on the loose.
The incident took place at Debsirin Nonthaburi School, in the Bang Kruai district of Nonthaburi province, with people being urged to avoid the area by police.
"Anyone trapped inside a building, hide, close everything tightly, and wait for rescue personnel to arrive," the police has just posted on its Facebook page.
According to reports at least 20 people have been injured as well as the two killed.
The force have identified the perpetrator as a student.
Thai police and local media have said the alleged gunman is now dead.
Officials have asked people to avoid the area as they remain at the scene.
