The boy, who told rescuers his name was Sandeep, was carried on a stretcher from the scene in Jalandhar, a town in Punjab state, and taken to a nearby hospital.
Workers continued searching for more people buried when the three-story factory buckled near midnight Sunday, while workers were inside. Estimates for how many may still be trapped have ranged from a dozen to more than 100.
Six bodies have been found and 60 people rescued, including three with serious injuries, District Magistrate Priyank Bharti said.
Many of the factory's workers were migrants from other Indian states, including Bihar, Jharkhand and West Bengal. Sandeep said he was from Bihar.
He said he passed out when the building collapsed, and did not know how long he was unconscious before waking and finding himself in a small cavern closed off by broken concrete slabs. The two friends he was with were missing, and he does not know what happened to them.
The sound of rescuers nearby gave him hope, Sandeep said, and he screamed until he heard them respond. It then took six hours starting Tuesday night for the rescuers to finally free him Wednesday morning.
Punjab's Chief Minister Parkash Singh Badal promised $3,800 compensation to families of those killed, as well as a statewide audit of building safety and a separate investigation into why the factory was in a decrepit state.
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