Three decades had passed since their 1987 graduation from a technology high school in Argentina, but they had kept close through marriages, trips, jobs - mostly as architects - and children.
Some had played volleyball together in school, and as grown-ups, they would meet almost every week for traditional Argentine meat barbecues, or asados.
This week, they gathered in New York for a trip to mark their graduation 30 years ago - a celebration shattered when a man in a rental truck mowed them down as they rode bicycles on a path on the west side of Manhattan.
Five of the group of 10 died. Police called it a terrorist attack.
They hailed from Rosario, Argentina, the country's third-largest city and the hometown of international soccer star Lionel Messi and guerrilla leader Che Guevara.
"It hurts us to think that these are people who walked the same school halls as we did or that studied in our same classrooms," said Agustin Riccardi, a senior at the victims' alma mater, the Polytechnic School of Rosario.
The Argentine tour group formed the bulk of the eight deaths from Tuesday's attack, victims who reflected New York's status as a top tourist destination and capital of finance and technology.
The others were a Belgian mother of young sons, a new college graduate working as a software engineer, and a doting son who had recently lost nearly 100 pounds and was getting a bike ride in between meetings at his World Trade Center job.
Now, friends and relatives are remembering the victims - and recounting the circumstances that led them to New York.