When the killers with the submachine guns burst into a suburban liquor store here to rub out two patrons, it marked the most bizarre turn yet in the increasingly common drug violence of South Florida.

Sure, there had been a running submachine gun battle on a main Miami highway between two carloads of heavies shooting over the hood of a passing carload of teenagers. And sure, the cops had found the body of a strangled Colombian drug figure in the trunk of one of those cars, a black Audi. And sure, there had been at least 37 killings tied to drug trafficking in the Miami area before the liquor store hits on July 11.

But the killings at Crown Liquors, in the fashionable Dadeland Mall, still marked in terrifying fashion the growing and absolute brazenness of what one presecutor calls "the crazy Colombians." By dint of their willing violence and their vast supplies of marijuana, cocaine and methaqualone, the Colombians have become the preeminent force in what is now the nation's capital of drug trafficking and importation - Miami and South Florida.

In just a few years, narcotics smuggling has become so extensive and lucrative here that by some estimates it has surpassed tourism as the biggest industry. And an industry it is, estimated in the billions.

It is a sophisticated international commodity business where brokers, using telephones and Telex, bring Colombian suppliers and local importers together. Millions of dollars are transferred electronically - a debit to one bank account, a credit to the other - through normal or almost normal banking channels.

Legitimate businesses serve as covers to hide illegal sources of unbelievable cash; other businesses simply profit from the sale of boats or other paraphernalia incidental to the trade.

And with so much illicit money to be laundered and moved about, state and federal officials openly fear for the role of, and the impact on, Miami-area banks. Already, enough has happened to justify those fears.

"I wouldn't say Colombia has annexed South Florida," observes William Richey of the state attorney's office in Dade County, "but they have made it a free zone."

A free zone: Murders are common, arrests for them few. Traffickers easily come up with, then leave behind, bail-bond money in six figures; it is little compared to their earnings. Aliens construct a maze of identities with passports perfectly forged in Colombia. Colombian crewmen arrested time and again in international waters with tons of marijuana return soon after their deportation.

"We're involved with people who aren't part of our general society," says Richey, "people who have large amounts of money and are extremely violent. Our laws for bond, for trials, are simply not equipped to deal with them."

So it is a "free zone."

And behind it all is cash, vast amounts created from marijuana shipped in by the ton, pure cocaine in wholesale lots, and millions of "downers" stamped out in tablets in Colombia by an old pharmaceutical die-and-punch.

The total amount of money will never, can never, be known. But it has, by the accounts of law enforcement officials and prosecutors and grand juries, left behind handsomely visible traces of its presence here.

It is visible, they allege, in the $1 million in cash that Felix B. (Felix the Cat) Vicknair spent between May and September 1976 on purchases of, and down payments on, a shopping center, a yacht and three houses.

It is visible, they say, in the $100,000 bond a Colombia-born Miami grocer skipped out on after he was charged with cocaine distribution; he was rearrested under an assumed name in New York, where he also owned a house.

And it is visible, authorities testified, in a few of the Spanish bank deposits of Miami businessman Jose Medardo Alvero-Cruz, a Cuban-born Bay of Pigs veteran. There was$1 million on Dec. 15, 1975; $315,000 on March 2, 1976; $950,000 the same day; $800,000 two weeks later.

But less visible and barely imaginable is the $12 million profit that two gang dealers claimed to have earned while importing what federal officials say was 500 tons of marijuana in a 16-month period.

Beyond all that is the $500-million-a-year organization state authorities claim they broke up by infiltrating it with an informant, two undercover investigators and wiretaps and video tape recorders.

Seven of every 10 pounds of marijuana seized last year in the United States by Drug Enforcement Administration agents were impounded in Florida. Of the 4.6 million pounds seized by U.S. Customs agents nationally, 4 million pounds were attributed to operations in Florida.

Twenty-six percent of DEA's cocaine haul of 1,759 pounds was seized in Florida; for Customs it was 57 percent.

And in the last six months has come the flood of methaqualone, commonly known by the brand name Quaalude.

Once Mexican supplies of marijuana were exterminated and cocaine became chic, the Rio Grande gave way to the Caribbean for traffic - and there was Florida: 8,246 miles of shoreline offering the isolated desolation of ten thousand islands and the protective bustle of a pier just down the street from Customs headquarters.

Florida is rich in airfields, and no point in the state is more than 70 miles from either the Atlantic or the Gulf of Mexico.

Then, too, there are the people: Spanish-speaking Latins, many of them poor, here legally and illegally, to deal with crews and suppliers; Bay of Pigs veterans whose anti-Castro training, prosecutors say, also taught them everything a drug trafficker needs to know; and the Colombians, with families and suppliers back home.

Those Colombians have dramatically changed the nature and the scale of drug-import operations here. At least five known organizations exist in an intricate system of supply and distribution.

It is among themselves that they now war, a seemingly endless cycle of killings - not for money, not for control, not for territory, but rather, as Archie Bunker said, because revenge is the best way to get even.

The Colombians are not the only ones accused in the drug trafficking here. There are also Cubans. One of them was Alvero-Cruz, who emigrated here and subsequently tried to help topple Fidel Castro at the Bay of Pigs. Alvero-Cruz was indicted last year in an alleged $7.2 million cocaine conspiracy - reportedly a single deal involving 123 kilos.

Testimony by a federal drug agent during a bond hearing (Alvero-Cruz posted a $50,000 surety bond and $450,000 worth of Miami business and residential holdings) involved Alvero-Cruz's bank deposits in Spain. That is where, the agent said, Alvero-Cruz has three apartments ranging in value from $58,000 to $101,000, as well as a Cadillac, a Mercedes and a Rolls Royce.

He had also apparently obtained traveling papers from the United States, Cuba and the Dominican Republic. Not long after his arrest a year ago, Spanish police said his checking account contained $1.6 million.

The indictment against Alvero-Cruz was dismissed in June when a government witness abruptly refused to testify.

A lawyer for Alvero-Cruz describes him to the Miami News not as a Cuban drug figure but as a successful businessman who is "very happy with the American way of life."

Besides Cubans, old-fashioned organized mobs are "in here and active," said Atlee Wampler, head of the U.S. Justice Department's organized-crime strike force in Miami. Wampler spoke one day after a reputed Chicago mob figure, Frank Ammirato, was sentenced to 26 years in prison on drug and weapons trafficking charges in Miami federal court.

There is, too, a multitude of individuals - small businessmen - as well as relatively smaller organizations. The attention, thought, is on the Colombians.

In recent years, said Allen R. Pringle, special agent in charge of the DEA Miami office, Colombians have moved from just supplying drugs to importing and distributing them.

But authorities believe this growth in Colombian activity is not behind the cocaine wars. "There is enough for everybody to get rich," Pringle said. "There is so much cash money the traffickers don't have time to count it; they weigh it."

"The money is unbelievable, millions and millions of dollars," said Richey in the state attorney's office. He cited one raid that netted 33 pounds of cocaine and $950,000. In cash. CAPTION: Picture 1, In Latin feud, two liquor customers were killed by machine guns in fashionable Miami shopping center. The Miami Herald; Picture 2, After this car sped along a turnpike spewing machinegun bullets, police found a body in the trunk. The Miami Herald