Members of the family of one of the six Kansas City, Mo., firefighters killed in an explosion blamed on arsonists weep during a memorial service Saturday at Arrowhead Stadium. The six were killed Tuesday when about 50,000 pounds of ammonium nitrate exploded when they were battling a trailer fire at a highway construction site. An estimated 2,500 firefighters and public safety officers attended the service as well as 5,000 private citizens. Police have received 50 to 75 tips on possible suspects, most of the tips coming after Wednesday's announcement of a $35,000 reward.