Manila, March 27 -- A total of 31 individuals were arrested during an intensified anti-drug dragnet in San Pedro, Laguna, earlier this week.

Twenty-eight of those tested positive for illegal drug use, according to the National Bureau of Investigation (NBI), which conducted the operation on Wednesday.

In a news release Thursday, the NBI said authorities recovered approximately 30.5 grams of suspected shabu during the operation. No amount was indicated.

The raid stemmed from multiple search warrants issued by Judge Nida Tabulada-Gravino of San Pedro City Regional Trial Court Branch 169, and was simultaneously carried out in Barangays San Antonio and Cuyab.

The NBI Dangerous Drugs Division spearheaded the operation, working alongside oth...