(CNN) -- Four people were injured and transported to a hospital after an explosion at the University of Missouri, officials said.
The explosion was believed to have been caused by combustion of gases that were being used in a research experiment, the university said.
The blast happened at about 2:15 p.m. (3:15 p.m. ET), and may have involved gases including hydrogen and nitrogen, the university said.
The building where the explosion happened houses the university's biochemistry department. The building was occupied at the time of the blast and was evacuated, the university said.