Firearm-related assaults on Los Angeles roadways.

During the summer of 1987, we investigated a series of firearm assaults occurring on Los Angeles County (California) roadways. Using law enforcement records, we identified 137 incidents of roadway assaults with firearms. Of these 137 incidents, 39% were brandishings and 61% were shootings. Of the shootings, 20% resulted in injuries; two were fatal. We compared the findings for June through August 1987 with findings for earlier years and found that the incidence rate of freeway firearm assault had increased each year from 1985 through 1987 for both freeway shootings and brandishings. We also found a positive association between freeway congestion and freeway firearm assaults in 1987.