The Narcotics Control Bureau (NCB) says it seized MDMA pills "in commercial quantity" on Saturday by intercepting a car headed for Hyderabad.
The central agency made the arrests following a "specific tip-off". The car — registered in Andhra Pradesh — was intercepted at the Devanahalli toll plaza in northern Bengaluru.
While all the four people travelling have been arrested, only one of them possessed the MDMA pills. He is a native of Visakhapatnam. Others are from Hyderabad and Bihar.
Under the stringent NDPS Act, more than 10 grams of any illicit drug constitutes commercial quality, according to a senior officer.
After questioning the four men, NCB officers raided their "drug supplier" in Bengaluru and seized a small quantity of high-grade ganja from him.
The four men are part of a drug syndicate supplying illicit drugs at parties and pubs as well as to individuals in Hyderabad, the NCB said.