Al Jazeera speaks to Mark Follman, senior editor at Mother Jones magazine, where he leads research on mass shootings in the United States.
Speaking to Al Jazeera's Sami Zeidan from Indianapolis, Indiana, Follman said the frequency of mass shootings have increased in the US and that "it's been a record year in terms of casualties" with seven shootings in 2012.
Follman, who researched 61 mass shootings, said 35 of the cases were murder-suicides. Another seven shooters died in police shootouts, often referred to as "suicide by cop", trends that he says highlight the fact that "the vast majority of these people have serious mental health problems".
Though he said politicians will often say the immediate aftermath of a shooting is not the time to debate the nation's gun control policy, Follman said "accessibility to weapons is obviously a key factor to this problem". He referred to "a wave of state gun laws that have made gun restrictions looser and looser".