Three Americans were wounded, one seriously, when unidentified assailants hurled a bomb at a bus carrying 28 U.S. soldiers north of the Honduran capital of Tegucigalpa, the U.S. Embassy said. Two Honduran passers-by were also injured, police said. An embassy spokeswoman said the Americans were returning to the military base at Palmerola after a brief training exercise in Comayagua, about 40 miles northwest of the capital, at the time of the attack. It was the second attack on American troops in the country this month. On Feb. 1, seven vehicles carrying more than 30 U.S. soldiers were attacked by gunmen in northern Honduras, but no one was injured.