In Goa, four persons belonging to a right-wing group were detained today in connection with the explosion in Margao town. They are alleged to be belonging to the group linked to Malegaon blast accused sadhvi Pragya Singh Thakur. Two members of the outfit were killed in the blast on Friday. Police are probing the links of right-wing group Sanatan Sanstha with the blast that took place at 9.30 last night when explosives kept in a scooter went off on a busy street in Margao. Within half an hour of Friday's explosion, bomb disposal squad detected and defused another bomb with an electric circuit, a clock, four gelatin sticks and a detonator at Sancoale, 20 km from the blast site. Home Minister Ravi Naik said the explosives may have got triggered before being planted at a designated spot. He said, they wanted to disturb a traditional Diwali-eve event 'Narakasur' effigy competition in the heart of the town as the blast took place only a few metres away from the competition venue. Terming the incident very serious, the Home Minister said he hasasked police to investigate without any political interference. Police raided Sanatan Sanstha headquarters at Ramnathi in Ponda town, 20 km from Margao, following the blast and four persons owing allegiance to the Sanstha were detained for questioning.Meanwhile, the Sanstha has denied the allegations against it terming them as baseless.