Authorities were conducting a routine inspection aboard the MSC Carlotta last month when a worn, teal shipping container caught their eye: The pins that held the containers’ doors in place appeared to have been doctored.

The Carlotta, a container ship, had just arrived in Newark, New Jersey, from Buenaventura, Colombia, and the teal container was supposed to contain dried fruit. Instead, officers opened the doors to find something that stunned even the most experienced customs agents: 60 tightly wrapped bundles of white powder, each the size of a small trunk.

The bundles turned out to be 3,200 pounds of cocaine, the largest drug shipment to be intercepted at Port Newark in a quarter-century, a bounty worth $77 million on the street, authorities said today.

The discovery of the shipment underscored the reality that legal ports of entry remain the main channel through which illicit drugs flow.

The seizure Feb. 28 also suggested the city’s market for cocaine was resurging, officials said, after several years during which heroin and fentanyl, a powerful synthetic opioid, had dominated New York’s illicit drug scene.

Ray Donovan, head of the Drug Enforcement Administration office in New York City, said dealers have begun combining fentanyl with cocaine, creating a new and deadly product. He said the giant cocaine shipment was a sign that traffickers were pushing “to build an emerging customer base of users mixing cocaine and fentanyl.”

“This record-breaking seizure draws attention to this new threat and shows law enforcement’s collaborative efforts in seizing illicit drugs before it gets to the streets and into users’ hands,” he said.

Investigators from the Department of Homeland Security were trying to determine where the drugs came from, and how they ended up in Newark. Authorities said today that no arrests had been made.

The operation included officers from Customs and Border Protection, the DEA and the New York Police Department. The port in Newark is one of the country’s largest and is a hub for illicit drugs from China and Mexico to enter the United States.

Cocaine has taken a back seat in recent years to opioids like heroin and fentanyl, officials said. Heroin is often cut with fentanyl to make it more potent, a trend that has caused an increase in overdose deaths.

Recent months, though, have seen the same tactics being used to cut and increase the city’s cocaine supply. It has concerned authorities enough that Donovan issued a public warning late last year to residents and tourists saying New York’s cocaine supply may be laced with fentanyl.