Authorities caught two illegal immigrants attempting to smuggle nearly half a million dollars in heroin Wednesday hidden in caulking tubes at a California bus station.

U.S. Customs and Border Protection agents conducting routine checks of identification at a Greyhound Bus Station in Blythe, California made the arrests after finding two Mexican men in violation of their immigration status. Concealed in caulking tubes stuffed inside their luggage, agents found 19 packages of heroin, reports the Associated Press.

Authorities seized more than 20 pounds of heroin and estimate the total value of the haul at more than $400,000. The unidentified men face immigration and narcotics charges, but authorities are not yet releasing specific information on the case.

The relentless efforts of drug cartels and domestic traffickers continue the steady flow of fatal narcotics into America’s cities, fueling overdose deaths throughout the country. Heroin claimed nearly 13,000 lives in 2015 and officials estimate more than 90 percent of heroin in the U.S. is flowing in from Mexico.

Authorities arressted nine Dominican nationals in April after decapitating a massive narcotics supply chain funneling drugs into the U.S. from Mexico. The operation employed smugglers to transport massive quantities of heroin and cocaine from Mexico across the border, which was then stored for sale at stash houses in Cranston and Woonsocket, R.I. for distribution in Massachusetts and Connecticut.

Officials say drug smugglers are getting more creative with the methods they employ for getting narcotics into the U.S. Authorities arrested a man at Dulles International Airport April 20 after arriving on a flight with a bag of lollipops containing nearly two pounds of heroin.

Officers searching his belongings found the bag of lollipops, which one agent found suspicious. Authorities discovered heroin smuggled inside the lollipops after smashing one of them open.

Oddly enough, after conducting an interview, CPD officers concluded the unidentified man had no idea he was transporting heroin within the lollipops and did not get charged.

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