Photos: Five years later, Boston Strong

Red Cross volunteer and Boston hero Carlos Arredondo (right) participated in the Blessing of the Athletes service at the Old South Church on Sunday. Jessica Rinaldi/The Boston Globe/Getty Images

At 2:49 p.m. on April 15, 2013, two explosions on Boylston Street forever changed the Boston Marathon -- and the people involved. Friends, family and fans paid tribute over the weekend to remember 29-year-old Krystle Campbell, 8-year-old Martin Richard, 23-year-old Lingzi Lu, 27-year-old MIT patrol officer Sean Collier, and the survivors.