WATCH: An Oklahoma City bombing survivor on why he’s worried about extremism today

Dennis Purifoy survived the largest act of domestic terrorism in U.S. history, the Oklahoma City bombing in 1995. Sitting in his cubicle on the ground floor of the Alfred P. Murrah Federal Building, he saw the flash of an explosion on his computer screen and was covered by debris. Sixteen of his co-workers and 24 visitors died. The attack opened his eyes to the reality of hate and terrorism, and he now urges law enforcement agencies to pay more attention to the rising threat of far-right extremism in the country. He believes that the divisions and polarizations in society make it easier for people to think in terms of "me or us versus them," and he is more concerned about it today than he has been in a while.