The death toll from last week’s fire at a converted warehouse in Oakland, California is at 36 but may go higher, as crews continue to search through the debris for more victims.

The cause of the blaze has not yet been determined. Authorities say the high number of fatalities is due to the difficulty people inside the building had in getting out quickly. According to news sources, the warehouse was being used as an artists’ colony and a number of internal structures were built without permits, leading to what is being described as a maze-like interior crowded with wooden objects. A single wooden staircase was the only access between the  two floors.

The Oakland fire is the deadliest fire in a single building in more than a decade, according to the National Fire Protection Association (NFPA), which notes that fires in “assembly occupancies” – like nightclubs, theatres and auditoriums -- have shown to be some of the most deadly when the proper features, systems and construction materials are not present.

NFPA code provisions mandate that a considerable number of safety systems and features be present in order to keep everyone safe should an unwanted fire occur. The level of safety provided is not the result of any single safety system or feature, but rather is achieved through the combination of multiple safeguards that are provided.