Abul Hashem, owner of Hashem Foods Ltd in Bangladesh, was arrested Saturday after 52 people died in a fire at the factory late Thursday.

According to fire officials, many of the victims died because they were trapped inside the building by an illegally locked door. Officials also said that children were among the victims and a separate inquiry into the use of child labor was launched. Four of Hashem’s sons were among eight people detained by police, who said all could face murder charges.

The fire started Thursday night on the ground floor of the six-story facility. The United News of Bangladesh agency reported that many workers jumped from the top floors of the factory, with more than 25 suffering injuries. Officials said the blaze was fueled by chemicals and plastics that were stored inside the building.