The line outside St. Joseph Church on Monday for the funeral of 29-year-old Krystle Campbell stretched down the block.
Campbell was one of three people killed near the finish line a week ago. The restaurant manager had gone to watch a friend finish the race.
In addition to the mourners, union members and a local motorcycle club showed up to stop a church group from disrupting the funeral.
Teamsters Local 25 President Sean O'Brien says the union members planned to stand in front of protesters to block them from the Campbell family's view.
Wallie Hawkins says his motorcycle club will rev their bikes to drown out protesters.