MUMBAI, India — The news in Mumbai, an economic driver of India, was horrifying but sadly familiar. A five-story apartment building collapsed Tuesday morning, burying many residents under tons of concrete and debris.

At least 12 people died and as many as six others were feared trapped in the rubble of the collapse, whose cause was not yet known.

A severe housing shortage and lax regulation in India have resulted in too many people crowded into old, weak and substandard structures.

The building, known as the Saidarshan, was nondescript, at the end of a cul-de-sac in a lower-middle-class neighborhood of Ghatkopar, an eastern suburb of Mumbai. A nursing home, unoccupied at the time, took up the ground floor. Apartments on the upper four floors were filled with residents when the building shuddered and pitched to the ground about 10:45 a.m. Soon, cries for help, wailing sirens and desperate moans of trapped men, women and children ranging in age from 3 to 80 filled the cul-de-sac and nearby streets.