MADRID , Spain ( CNN ) -- 15 U.S. embassies in Europe receive mail containing white powder . Tests show powder harmless in 15 cases ; results pending in 16th case . Madrid embassy official in U.S. : ` ` We know where the package is coming from ''
15 U.S. embassies in Europe receive mail containing white powder . Tests show powder harmless in 15 cases ; results pending in 16th case . Madrid embassy official in U.S. : `` We know where the package is coming from ''