Vuong Thai Duong, secretary of the Khuong Thuong Ward in Ba Dinh District, said the fire broke out at around 2 p.m. Thursday in a house on Tam Khuong Street. Inside were four people, including three students of the Thuy Loi University aged 24.

On Thursday morning, the four invited a friend over for a meal. At around 12 p.m., they burned joss paper as offerings to the Kitchen God, a tradition before the Lunar New Year Festival, in front of the house. Then they had lunch inside the house. Four of them slept inside the house while another went outside, locking the front gate.

At around 2 p.m. when the man returned, the house was already on fire. Three firefighting trucks with 15 firefighters, were dispatched to the scene soon after, but the four people inside were found dead.

Police are investigating the incident and further details were not available.

Joss paper burning is a long-standing tradition in Vietnam, especially during auspicious occasions like the Lunar New Year Festival (Tet) and death anniversaries.

Authorities have been urging people to abandon the practice because of the air pollution and the financial cost it causes.