Police say they believe sparks from welding equipment caused a deadly blaze in a fireworks factory near Indonesia's capital this week that killed 48 people.
"The witnesses' testimonies and forensic test revealed the cause of the fire was the welding equipment sparks which spread to the fireworks material," said Jakarta police spokesman Argo Yuwono.
The factory owner and the company's operations manager have been detained by police. The whereabouts of the welder was not immediately clear.
The men are suspected of negligence.
Police said the owner is also suspected of employing underage workers at the factory in the manufacturing hub of Tangerang, outside of Jakarta.
Witnesses say a huge explosion was head at the factory about mid-morning Thursday, followed by smaller explosions and an inferno that engulfed the factory, causing its roof to collapse.
Firefighters needed hours to bring the fire under control.
Industrial safety standards in Indonesia are often low and rules poorly enforced. Authorities say the factory had been in operation for about two months.
Officials say the death toll will likely rise as dozens of workers with extensive burns have been admitted to hospitals.