Singapore’s Central Narcotics Bureau (CNB) said Monday that it arrested 159 suspected drug offenders, including a 14-year-old student, in an island-wide anti-drug operation from May 6 to 17.

The CNB seized 937 grams of heroin, 376 grams of Ice, and 161 grams of cannabis, among other drugs, with an estimated street value of 221,000 Singapore dollars (164,000 U.S. dollars).

Investigations into the suspects are ongoing.