Boston Marathon organizers say two bombs went off near the finish line of the race, killing three and injuring at least 170 people, according to the latest reports.
In San Francisco, cable cars average about an accident a month and routinely rank among the most accident-prone mass transportation modes in the country per vehicle mile traveled annually.
Government employees experienced a rate of nonfatal workplace violence that was more than three times the rate for private-sector employees during 2011.
Deputy Secretary Jane Holl Lute has been involved in DHS since 2009, and has led the charge in sharing air passenger information with the European Union.
Police reportedly found three unregistered firearms in the man's vehicle, along with ammunition. Unregistered firearms are illegal in the District of Columbia.