Ly Hao Nam fell into a 35-meter-long pile at the site in the southern Dong Thap Province on Dec. 31 and was confirmed dead four days later after intense rescue efforts failed.
Colonel Tran Trung Quoc, spokesman of Dong Thap Police, said: "This accident was a rare and painful occupational accident. The contractor and many others made great efforts to rescue the boy, but we could not save him.
"The construction site was fenced and there was only one pile shaft left and it was to be filled that afternoon, but the children took advantage of workers' lunch break to sneak into the site, resulting in the tragic accident."
Witnesses said the boy had screamed for help for 10 minutes after falling in before going quiet.
The narrowness of the shaft thwarted rescuers’ efforts to get him out, and even getting his body out had proven very difficult.
The Roc Sen Bridge, the site where the tragedy occurred, is being built by the Dong Thap Department of Transport.