The deceased R Santhoshkumar of the Arasu Pannai area was a Class 6 student while the missing boy P Harish is also from the neighbourhood.
Police said the river was deep after desilting and rains, and the boys could not swim back. Passersby who noticed the boys struggling alerted the fire control room and personnel from Saidapet, Teynampet and Guindy launched a search. Santhoshkumar was rescued and rushed to the Govt Royalettah Hospital, but was declared brought dead.
Harish remained missing and the rescue personnel had to abandon the search due to poor light on Tuesday night. The ops resumed on Wednesday morning but is yet to meet with success.