Bhubaneswar. At least four people were killed and four others were seriously injured in a massive explosion at an illegal firecracker factory in Odisha's Khurda district on Monday. The incident took place near Bhusandpur village of Tangi police station area. The blast took place when the workers were making crackers for the Dola festival. Dola festival is celebrated during Holi. However, the exact cause of the explosion is yet to be ascertained. Khurda Collector Chakraborty said