A 10-YEAR-OLD BOY WHO DIED OF SEVERE BURNS ON SATURDAY BECAME THE SECOND FATALITY OF A FIRE BOMB ATTACK ON TWO BOGOTA BUSES THAT IS BEING BLAMED ON MARXIST REBELS, HOSPITAL OFFICIALS SAID ACCORDING TO REUTERS. THURSDAY'S BOMBINGS OF THE PACKED BUSES IN A WORKING-CLASS DISTRICT OF THE CAPITAL ALSO KILLED AN 11-YEAR-OLD BOY AND INJURED MORE THAN 20 PEOPLE, MANY OF THEM CHILDREN. THE ATTACK HAS OUTRAGED THE COUNTRY. ON FRIDAY SCHOOLMATES OF THE DEAD AND WOUNDED CHILDREN MARCHED IN THE RAIN THROUGH THE INGLES NEIGHBORHOOD TO PROTEST THE BOMBINGS, WHICH POLICE SAID WERE THE WORK OF THE REVOLUTIONARY ARMED FORCES OF COLOMBIA. SECURITY FORCES HAVE GONE ON THE OFFENSIVE AGAINST THE REBEL ARMY KNOWN BY ITS SPANISH INITIALS FARC, WHICH THEY EXPECT PLANS TO STEP UP ATTACKS AHEAD OF THE MAY 28 PRESIDENTIAL ELECTION. PRESIDENT ALVARO URIBE IS SET TO EASILY WIN A SECOND FOUR YEARS IN OFFICE, THANKS LARGELY TO HIS TOUGH POLICIES AGAINST THE FARC, WHICH HAVE REDUCED VIOLENCE IN THE COUNTRY'S FOUR-DECADE-OLD WAR. SECURITY FORCES ESTIMATE THE FARC, WHICH FUNDS ITSELF FROM COCAINE AND KIDNAPPING AND WANTS SOCIALIST REFORM IN A COUNTRY WHERE MOST PEOPLE LIVE IN POVERTY, HAS ABOUT 17,000 MEMBERS. BUT IT HAS LITTLE SUPPORT IN THE CITIES WHERE MOST COLOMBIANS LIVE.