They said they shot blanks from their weapons.
Sgt Saringkarn Taweecheep and Sgt Kacharat Niemrod from the fifth Cavalry Battalion were questioned for over six hours.
They said they were instructed to maintain peace and safety near Bon Kai area on Rama IV Road on May 15, 2010 between 3pm and 8pm. There were reports of deaths and injuries in the vicinity on that day.
DSI deputy chief Prawet Moolpramuk, in his capacity as chief of the committee investigating the violence which resulted in 91 deaths, said that experts will examine the mentioned rifles.
“If no other witnesses are required and evidence is complete, their testimonies will be added to the investigation on dead protesters at Bon Kai,” he said.
He added that the two soldiers were asked to testify due to their appearances in a much-publicised video clip.
Earlier on Monday, former premier Abhisit Vejjajiva and ex-deputy premier Suthep Thaugsuban separately testified to the DSI over the Red-Shirt riots in Bangkok in April-May 2010 when 91 deaths were reported.
Mr Abhisit spent over seven hours before the DSI while Mr Suthep was questioned in a 12-hour marathon until Tuesday morning.