Chennai, Oct. 20 -- Four people were killed on Sunday after "country-made" firecrackers stored in a house at Thandurai exploded, Avadi police said. Several portions of the residential premises has also been damaged in the explosion, they said adding Fire and Rescue Services personnel doused the fire. An Avadi Commissionerate police official said four persons died in the explosion adding the residence appeared to have been used as a storage facility and as a place of retail sale as well.A probe is on to ascertain the cause of explosion, the official added. Banned Chinese firecrackers, worth about Rs.5 crore, concealed in a container that arrived in a cargo vessel at the Tuticorin port was seized by authorities and four men have been arrested, police said on Sunday. Officials of the Directorate of Revenue Intelligence asked the staff to open the container to verify if the goods that had arrived matched with the description shown in the invoice of consignment....