Above: A Nexstar Media Wire video explaining what fentanyl is. SAN DIEGO (FOX 5/KUSI) — Border Patrol agents seized nearly five pounds of fentanyl pills and arrested two suspected smugglers in eastern San Diego County last Thursday following a short pursuit along Interstate 8, U.S. Customs and Border Protection said. Officers first encountered the suspects around 4 p.m. as their vehicle approached the Border Patrol Immigration Checkpoint on I-8 in Pine Valley. According to CBP, agents directed the driver of the vehicle to move into secondary inspection but he did not, instead speeding off west on I-8. After a short pursuit, the driver lost control of the vehicle and crashed near the highway's exit at East Willows Road near Alpine. Homicide investigation underway in Oceanside following welfare check The driver and a male passenger both sustained injuries that required treatment on site. No other injuries were reported. As the two were receiving medical attention, CBP says Border Patrol agents discovered eight plastic-wrapped bundles inside the vehicle. The wrapping appeared to be consistent with smuggled narcotics, federal officials add. The drugs were then brought back to the checkpoint where the packages for further inspection. According to CBP, the pills tested positive for fentanyl and weighed an estimated 4.73 pounds. Federal officials turned the case over to the Drug Enforcement Administration for further investigation, while the vehicle and drugs were put into Border Patrol custody. Both the driver and passenger are facing unnamed federal charges, CBP adds. No details were provided about the two suspects' identities, including whether they were U.S. citizens.