The terror investigation surrounding 24-year-old Colorado resident Najibullah Zazi has now resulted in a nationwide alert to transit agencies. The FBI and Department of Homeland Security sent out warnings that police should be on guard for attacks by hydrogen-peroxide–based explosives. According to the Washington Post, federal officials "called the notice 'precautionary', and said it included possible countermeasures such as random checks of stations, trains and buses." [WP]