ROSARIO, Argentina — Their big trip to New York had been decades in the making.

Thirty years ago, when they were all still high school students in this industrial city in Argentina, 10 young men promised to celebrate their reunion somewhere in style.

“In 30 years, we have to go on a trip,” said Cristian Ciancia, a fellow graduate, recalling the pledge.

The friends eventually settled on New York, but the cost was too high. So Ariel Erlij — one of five Argentines killed in the terrorist attack on Tuesday in Lower Manhattan — did not think twice before helping to pay for flights, friends said.

“When any friend, any acquaintance, needed anything, he never hesitated to offer a hand,” said Mr. Ciancia, who was not on the trip.