Authorities in Boston have seized more than 33 pounds of fentanyl - enough to kill millions of people - in connection with one of Massachusetts' biggest drug busts ever.

Prosecutors said the synthetic opioid was being sold on the street by a drug gang with links to Mexico's notorious Sinaloa Cartel, the drug organization once led by Joaquín 'El Chapo' Guzmán.

The seize came at the climax of a six-month wiretap probe called 'Operation High Hopes,'

A lengthy wiretap operation by a joint task force including Drug Enforcement Administration agents and Boston police resulted in an early-morning sweep of the drugs and 37 suspects

Edward Soto-Perez, 43, of Boston was the first to be arrested late last year and he allowed wiretaps to be set up for others tot be caught in the drug operation

'I want to be clear about the size and scope here,' District Attorney Daniel Conley said. 'Massachusetts' fentanyl trafficking statute covers quantities greater than 10 grams. That threshold represents less than 1/1000 of the quantity we've taken off the street.'

'Individuals who buy and sell at this level aren't users,' Conley said. 'They're not small-time dealers, either. They're certainly not selling to support a habit. They're trafficking in addictive substances that claim more lives in Massachusetts than all homicides, all suicides, and all car crashes, statewide, combined.'

He said that the number of overdoses the seized fentanyl could have caused 'is truly staggering.'

In total, 77 pounds of drugs were seized, including heroin, cocaine and opiate tablets in addition to the fentanyl. Authorities said they confiscated $300,000 in drug money

The biggest name authorities managed to catch in the probe was Robert Contreras, 42, of Boston. It's believed he has a direct link to Mexico's vicious Sinaloa cartel

Conley called the investigation 'one of the longest, most far-reaching and most successful state wiretap investigations in Massachusetts history. ... But it did not stop there. It continued up the ladder to identify a second group at the top of the domestic pyramid, one with direct ties to Mexico's Sinaloa cartel.'

The Boston Herald reported 33-pounds of fentanyl would be enough to kill more than 7 million people in its raw form - more than the population of Massachusetts which is 6.8 million.

Michael J. Ferguson, DEA's special agent in charge of the New England Division, likened fentanyl to a weapon of mass destruction.

'You take a sweetener packet that has 1,000 milligrams in it that you put in a cup of coffee. It takes only two milligrams and it's lights out for an individual,' Ferguson said. 'We're talking a couple of grains of salt or sand. It can kill you if you inject it in your arm, if you snort it up your nose or simply breathe it in the air. Drug traffickers are now lacing fentanyl not just with heroin, but with cocaine as well. As well as in pain pills, counterfeit pain pills made to look like Percocet.'

The biggest name authorities managed to catch in the probe was Robert Contreras, 42, of Boston. He was arrested at his home Thursday and is being held in lieu of $1 million bail.

The probe's initial focus was one of Contreras's customer, Edward Soto-Perez, 43, of Boston. He was the first to be arrested late last year.

Soto-Perez was clever and extremely diligent in covering his tracks. He used couriers to make deliveries and take cash payments. He switched cars regularly to foil court-authorized GPS tracking. And he would make as many as five sudden turns in the span of a mile to spot police surveillance teams.

He allowed police to wiretap him which eventually led to the revealing of his stash houses and the identities of his suppliers with Conteras being his largest supplier.

36 others were also arrested in the probe which saw investigators seized cocaine, heroin, two guns and $300,000 in cash.