The deceased have been identified as Rahul (22), Budhram (19), Amit (18) and Vikas (21), who along with some of their friends had gone for a swim at the Yamuna canal in outer Delhi's Alipur area, police said.
When two of them went into deep waters and lost control, the other two dived in to rescue them and all four of them went untraceable within minutes.
Their friends raised an alarm and a rescue opertion was launched jointly by fire department and district administration.
