The accident happened at Yellow School - Memorial Drive Presbyterian Church just after noon.
According to the Houston Fire Department, pre-school students at the 240 block of Blalock Road were conducting some type of science experiment outside when a flash blast occurred.
Of the 12 students who were injured, 11 of them suffered burns, one student was trampled and six of them were taken to the hospital. All of the students are 3-years-old, a Village Fire Department official said.
"It was an experiment that went wrong. There was a brief moment of flame and it was put out fairly quickly," church business administrator Bob Giles told ABC13.
The victims were taken to Memorial Hermann Hospital in the Texas Medical Center treatment.
Crews from Houston and Village fire departments were called to the scene. The fire marshal and police are investigating the accident.
Parents have been notified about the incident. The other students at the school were not injured, according to Memorial Village police.
"We love these children. This is our church. We're praying for them," Giles said.
There's no word on what type of experiment the children were conducting and what chemicals were being used. null