Three teenagers have been arrested after allegedly trying to smuggle $143,000 worth of Fentanyl, a powerful opioid, over the U.S.-Mexico border.

U.S. Customs and Border Protection officers at the San Ysidro Port of Entry in San Diego thwarted the alleged narcotic smuggling attempts over the weekend after discovering the teens were carrying packages of fentanyl strapped to their bodies.

The first incident happened Friday, March 30 around 7:20 p.m.

CBP officers said they encountered a 17-year-old male Mexican citizen at the San Ysidro Pedestrian East border crossing.

CBP officers said they were conducting inspections at the primary booth and noticed inconsistencies with the teen. They did a visual search of him and discovered something odd on his back.

A CBP officer conducted a pat-down search for weapons and found the odd lump was two packages strapped to the teen's back. Officers said it was fentanyl weighing over 4 pounds.

The estimated street value of the fentanyl was $141,000.

Then, on Saturday, March 31 around 8:29 p.m., CBP officers said they encountered a 15-year-old male Mexican citizen at the same border crossing.

The teen was instructed to be examined further. CBP officers said that's when they noticed a bulge on the teen's back and found two packages strapped to him of fentanyl weighing just under 5 pounds.

The fentanyl carries an estimated street value of $143,000.

Ten minutes later, CBP officers at the same crossing encountered a 17-year-old male U.S. citizen. Again, officers said they noticed a bulge on the teen's back and discovered two packages strapped to him.

These packages of fentanyl weighed just under 5 pounds and also had a street value estimated at $143,000.

"These cases all involve juveniles allegedly attempting to smuggle a dangerous and lethal narcotic such as fentanyl. Fentanyl is known to be 50 to 100 times more deadly than heroin," said Pete Flores, Director of Field Operations for CBP in San Diego. "The dangers associated with the unfamiliarity of handling fentanyl can be deadly."

The teenagers were arrested and turned over to Homeland Security Investigations for further processing. CBP officers seized the narcotics.

The seizures from over the weekend come after CBP officers stopped two other suspected smuggling attempts by teenagers last week at the San Ysidro Port of Entry.