KARACHI – Two killed and four wounded in two separate blasts occurred here on Tuesday.A mysterious explosion occurred inside a dental laboratory situated in Block 13-D within the limits of Gulshan-e-Iqbal police station.According to details, the explosion occurred inside the laboratory when the deceased workers were busy making formula for making artificial teeth.Ayaz and Anwar died on the spot while the laboratory’s owner Faisal Siddiqui was critically wounded. Following the explosion, police and Rangers reached the site and cordoned off the area. Bomb disposal squad was also called at the blast site. According to the BDS officials, it was not an act of terrorism but the explosion occurred because of gas cylinder.Police said that the fire also erupted due to the explosion, resultantly Siddiqui sustained burn injuries and was taken to Burns Ward of the Civil Hospital Karachi where his condition was said to be critical. Meanwhile, a low-intensity blast took place on the top floor of the five-storey residential apartment situated near Nagan Chowrangi, North Karachi area. Police said that a man namely Altaf, his wife and brother Ejaz were wounded and taken to the Abbasi Shaheed Hospital for medical treatment. Police said that a manual improvised explosive device attached with the battery was placed outside the flat of Altaf and his brother Ejaz, who used to run his electrical shop downstairs of the apartment. He said that the victim Altaf mistakenly switched on the device. The officer said that only the detonator containing three grams of explosive was attached with the device without pellets.Police explained that unidentified culprits also placed the cricket ball contained explosive material outside flat few months ago. The motive behind the incident has yet to be ascertained while police suspected extortion mafia was behind the incident.