NEW DELHI — At least 43 people were killed Sunday morning when one of the worst fires in recent memory in New Delhi broke out in a cramped, commercial neighborhood, officials said.

The blaze erupted around 5:30 a.m. in a multistory building used for making paper products and purses. Atul Garg, New Delhi’s chief fire officer, said firefighters initially struggled to douse the flames because narrow lanes blocked access to the area, which is full of dilapidated buildings.

“This is the second-biggest fire in Delhi’s history,” he said.

The building in the Anaj Mandi neighborhood of northeastern New Delhi was packed with sleeping laborers when the fire broke out. Most of the victims were Muslim migrant workers from impoverished Bihar State in eastern India, The Associated Press reported. They earned as little as 150 rupees (about $2.10) per day making handbags, caps and other garments, it said.

Investigators blamed an electrical short-circuit for the fire, The A.P. reported. Safety standards are poorly enforced in India and are linked to many deaths.