I doubt that many readers of H&R are worried, but the answer is: Not at all likely. Here's some of the latest data from the Bureau of Justice Statistics.
The proportion of homicide incidents involving two victims has increased slightly from 2.7% in 1980 to 3.7% in 2008.
Homicide incidents involving three or more victims have also increased during this same period, but have remained less than 1% of all homicides each year.
For 2008 (the latest data available from BJS) the figures for all multiple victim homicides were:
—3.7% involved two victims
– 0.5% involved three victims
– 0.2% involved four victims
– 0.1% involved five or more victims.
In addition, overall U.S. homicide rates have been falling in recent years:
—The homicide rate doubled from the early 1960s to the late 1970s, increasing from 4.6 per 100,000 U.S. residents in 1962 to 9.7 per 100,000 by 1979.
– In 1980 the rate peaked at 10.2 per 100,000 and subsequently fell to 7.9 per 100,000 in 1984.
– The rate rose again in the late 1980s and early 1990s to another peak in 1991 of 9.8 per 100,000.
– The homicide rate declined sharply from 9.3 homicides per 100,000 in 1992 to 4.8 homicides per 100,000 in 2010.
Here's a chart of the longer term trend of the U.S. homicide rate:
That being said, condolences to the families and friends of the people murdered in Aurora and hope for the speedy and complete recovery of the wounded.