The woman, Marjina, was picking plastic refuse from the garbage dump near the Family Court in Farsh Bazar area, along with her husband Ansar Ali, 32, and their four-year-old son.
Around 5 pm, a loader, which was lifting the garbage nearby, suddenly hit the wall of the dump leading to its collapse, said Nupur Prasad, the deputy commissioner of police, Shahdara.
The garbage dump and the loader belonged to East Delhi Municipal Corporation (EDMC), the police said.
The trio tried to escape when they saw the wall collapsing. But were unable to escape as the wall came crashing down very fast, the police said.
The police said they have impounded the loader but its driver managed to flee the spot. A case has been registered and probe was on, they added.
Marjina and her family lived in New Seemapuri. They worked as rag pickers to earn their livelihood.