He has used a shotgun and a revolver from his father and he had a license to own the weapons legally. According to Police, most of the dead are students. The Governor of Texas, Greg Abbott said, "Lots of explosive devices were found at the school, on and off-campus.
It also included a CO2 device and a Molotov Cocktail. The shooter's information has been collected and it was a pre-planned attack. He also intended to kill himself afterward. But he gave himself up as he never got the courage to commit suicide."