Hassan (Karnataka), Dec 27 : Karnataka Police were grilling two persons, including a woman, in connection with the incident of mixer-grinder blast in Hassan city of the state, police said on Tuesday. The incident had taken place at a courier shop owned by one Shashi on Monday late in the evening in K.R. Puram Layout DTDC courier shop. The mixer-grinder was brought to his shop two days ago. When the delivery was made, the customer had refused to take it saying that it had not come from the appropriate address. The owner Shashi, out of curiosity had opened the parcel and found the mixer-grinder inside. He further attempted to test it. As soon as he switched it on, the mixer-grinder exploded. The intensity of the blast was such that the windows, doors and walls of the shop were damaged. The incident had triggered panic in the area. Hassan Superintendent of Police Hariram Shankar said on Tuesday that a team of experts from the Forensic Science Laboratory (FSL) visited the spot on Monday. The samples were collected and a case registered under the Sections 3 and 4 of the Explosives Substances Act, he stated. However, he had clarified that so far there are no clues gathered in the case which would indicate challenges to internal security. The lane where the blast took place has been barricaded and sealed off. The courier shop owner Shashi is being treated at the hospital. /IANS