District Superintendent of Police (Kollam) Harshita Attaluri yesterday led a crackdown on illegal sand-mining in the district. Raids were organized simultaneously at all the three police sub-divisions of Kollam, Karunagapally and Punalur in the district. The raids began at 6 a.m. Sources said the early morning raids surprised the sand mafia because yesterday mornings are usually parade time at police stations. As many as 56 cases were registered and 31 persons allegedly engaged in unauthorised sand-mining arrested following the raids. Over 26 vehicles were taken into custody. Twelve country boats and 4 mining motors were also seized. Eight cases were registered under the jurisdiction of the East Kallada station. Seven cases were registered under the Sasthamcotta police station and six each at the Chathannur and Ezhukone police stations.