A Confederate flag flown during a high school football game touched off tense conflict on and off the field Friday night and three players from Manual High School were injured, the principal said in a community letter Saturday. Players from Manual also told coaches that students on the visiting team, Weld Central High School, taunted them with racial slurs during tackles, according to principal Nick Dawkins’ letter. Weld Central, in Keenesburg about 40 miles northeast of Denver, has a Rebel as a mascot.