Write SQL query to solve given problem: How many weapons violation crimes have occurred in the Calumet district?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT SUM(CASE WHEN T3.district_name = 'Calumet' THEN 1 ELSE 0 END) FROM IUCR AS T1 INNER JOIN Crime AS T2 ON T2.iucr_no = T1.iucr_no INNER JOIN District AS T3 ON T3.district_no = T2.district_no WHERE T1.primary_description = 'WEAPONS VIOLATION'