In addition to strengthening the ATF's enforcement power, we need to attack gun trafficking at its source by limiting the high-volume gun sales that fuel trafficking from licensed dealers.

CNN: Commentary: Stop flow of U.S. guns to Mexico drug war

Though the motive for the terrorist attack at the race is still unknown, the source briefed on the investigation added that it should not be assumed that the brothers were radicalized because of their origins in the Russian Caucasus.

CNN: Suspects described as brothers from Russian Caucasus