Hong Kong Chief Executive John Lee apologized on Thursday and announced that his housing secretary, Winnie Ho, had resigned, after an investigation into the city’s deadliest fire in decades found inadequate regulatory oversight, according to France 24.

The fire began last November, engulfed seven buildings in an apartment complex in a northern suburban district, killed 168 people and displaced thousands, France 24 reported. According to the South China Morning Post, the report attributed the blaze to a combination of a lit cigarette and an abundance of combustible materials, and concluded that contractor PC&E and consultant Will Power were fully aware of the fire risks.