Lucknow | Fifteen people who died in the devastating fire that tore through a building in Lucknow's Aliganj area succumbed to suffocation after inhaling large quantities of smoke, with post-mortem examinations revealing that toxic fumes, not flames, were the primary cause of death, doctors said on Wednesday.

The post-mortem examination found no clear evidence of extensive burn injuries or deep wounds that could directly explain the deaths, the doctors associated with the examination process told PTI.

However, doctors observed swelling around the faces and eyes of several victims and detected soot and smoke particles inside their nasal passages, indicating that they had inhaled large quantities of smoke before their deaths.

"The post-mortem examination has revealed that all 15 victims died due to suffocation caused by smoke inhalation. No major burn injuries or grievous external wounds were found that could be attributed as the direct cause of death," a senior doctor involved in the examinations told PTI on condition of anonymity.

Based on the findings, doctors concluded that all 15 victims died due to asphyxiation caused by smoke inhalation.

The observations have been shared with investigating authorities.

Explaining the findings of the autopsies, the doctor said fires in enclosed spaces often turn deadly because of smoke and toxic gases rather than direct exposure to flames.

"In enclosed spaces affected by fire, oxygen levels can rapidly decline while toxic gases accumulate, creating conditions that can lead to suffocation," the doctor said.

"In many cases, trapped occupants do not get sufficient time or opportunity to escape. The deceased must have lost consciousness due to heavy smoke before their deaths," the doctor told PTI.

Senior doctors noted that fatalities in fire incidents are frequently caused by toxic gases present in smoke. When smoke engulfs a confined space, oxygen levels drop sharply, making breathing increasingly difficult.

The burning of plastic, foam and other synthetic materials can release poisonous gases such as carbon monoxide, which interferes with the body's ability to carry oxygen in the blood and can cause unconsciousness and death within a short period, they said.

A fire broke out in the Aliganj building on Monday, claiming 15 lives, most of them youngsters.

A devastating fire ripped through a three-storey commercial complex housing an animation centre on Aliganj's Usha Mehta Marg on Monday afternoon, killing 15 people, most of them students, and injured several others.

The tragedy triggered widespread outrage and prompted the Uttar Pradesh government to order a high-level probe into the incident.

Authorities have launched investigations into possible violations of fire safety norms, while the Lucknow Development Authority has issued notices over alleged regulatory violations linked to the building.

The state government has also announced compensation for the families of the victims and directed officials to inspect educational and commercial establishments across the state to ensure compliance with fire safety regulations.