(CNN) -- The death toll stands at 13 in Wednesday's blast at a factory in the eastern Chinese city of Nanjing, state-run Xinhua news agency reported, citing remarks by authorities on Thursday.
The explosion rocked an abandoned plastics factory in northern Nanjing's Qixia District, destroying nearby buildings. In addition, a fire caused by the blast destroyed a bus. Crews were dismantling the plant at the time of the accident.
Firefighters extinguished the blaze Thursday, and three more bodies were found when crews cleared debris.
At least 14 critically injured people were among 120 hurt. Of those badly injured, three received emergency treatment and were out of danger.
Authorities arrested three construction contractors and one official at the Nanjing No. 4 Plastics Factory who was responsible for the safety of the dismantling work.
Rescue officials said a gas leak caused the blast. That came after a propylene pipeline was damaged when workers used excavators to retrieve garbage, such as copper pipes.
Eight monitoring sites have been set up to check air and water quality in the area.
The latest monitoring results have initially found no pollution after the blast.
The report said electric power, water and gas service to households in the area had resumed.