Police investigating February’s deadly fire at the Banyan Tree Hotel construction site in Busan say appropriate fire prevention measures were not in place. 

The Busan Metropolitan Police unveiled the interim results of a nearly two-month-long investigation Monday, along with CCTV images from the day of the fire. 

The police said the fire, which killed six workers, most likely started when a subcontract worker cut a stainless steel pipe and attached another pipe on the first floor of the construction site. 

Police believe a spark from the welding work fell on the pipe insulation in the basement ceiling, after the spark made its way through one of the holes on the floor behind the pipes.

They found that during the welding work, no fire watcher was present and no fire-resistant clothes were placed over the holes on the floor. 

Police also found that a sprinkler in the basement had no water, while a sprinkler on the first floor did have water but its valve was locked in preparation for fire inspections. 

The police announcement comes after six people were arrested Friday, including the head of the construction firm charged with the hotel construction work.