Burning incense sparked the fatal Bronx fire that took the life of a 5-year-old boy and left the child’s mother critically injured, the FDNY said Wednesday.

The fire erupted inside an apartment on the fifth floor of a 15-story building in the Melrose Houses on E. 153rd St. near Morris Ave in the South Bronx about 9:30 a.m. Monday, officials said.

Medics rushed the little boy to Lincoln Hospital but he couldn’t be saved. His name has not yet been released.

His 38-year-old mother was taken to the same hospital in critical condition, police said. Two other people suffered minor injuries.

FDNY Fire Marshals determined that the blaze was sparked by burning incense. There were no working fire alarms present in the home, officials said.

Neighbors immediately suspected the blaze was caused by incense, which the victim’s family often used.

“I think it was the incense, you know because it smells so good on that floor,” neighbor Annmarie Lodge said Monday. “I think the little boy got up and was playing with the incense.”

“He was playing with the candle that lights the oil and that’s what happened – it started a fire,” Lodge speculated. “The mom was probably sleeping and the boy got out his room.”

The child’s father had just gotten home from work as firefighter put out the blaze, Lodge said.

“He saw everything,” she said. “The fire department, and everything.”

The fire was brought under control at 10:17 a.m., the FDNY said. Clothes, a mattress, a child’s blue plastic chair, and other debris covered the ground outside the building.