PROVIDENCE — In an investigation aimed at especially brazen drug dealing on street corners, the city police and federal drug agents have arrested 70 people on narcotics and weapons charges and are seeking to arrest another 27.

Law enforcement authorities began rounding up the suspects last week, punctuating an investigation nicknamed Operation Crackdown that was announced yesterday. Some corners where the drug peddlers stood three, four or five deep, depending on the weather or the time of day, have been cleared, said police Sgt. Fabio Zuena.

The operation incorporates a new approach in which seven suspects with minor criminal records were separated from the crop destined for arrest and will be offered what Police Chief Dean M. Esserman called “a second chance” to straighten out their lives and avoid another arrest.

Those seven — four juveniles and three adults — will be called into a room for a dose of “tough love” by their neighbors, community leaders and the police, Esserman said, and offered education, substance-abuse treatment and employment opportunities.

They will be told, he said: “You may not return to that corner. We don’t have to catch you. We’ve already caught you. We just have to have the [arrest] warrant signed the moment you return to that corner.” Then an array of social services will be pressed on them.

Operation Crackdown was described as unusual in its duration and scope. Beginning in April and lasting through last month, investigators researched the drug-dealing hot spots throughout Providence and focused on an area of Upper South Providence with the Lockwood Plaza public-housing development as the epicenter.

They identified 104 people as investigation targets, including the seven who are avoiding immediate arrest, and made a number of undercover purchases of cocaine and handguns. Esserman and Mayor David N. Cicilline said that list makes it “the largest narcotics and gun investigation” in Providence police history. Brian Crowell, assistant special agent in charge of the New England division of the U.S. Drug Enforcement Agency, said the 72 arrested are “the most ever targeted in a single drug investigation in Rhode Island.”

Investigators bought or seized four kilos of crack and cocaine and four handguns — there were 150 individual drug buys — and seized $38,000 in currency.

Operation Crackdown is inspired by the Urban League of Rhode Island, whose national organization wants to replicate the success of the so-called Highpoint Initiative in Highpoint, N.C. The Highpoint program, which has been popularized in academic law enforcement research, took aim at “open-air drug markets” by removing street dealers in an effort to reduce drug-related crime and violence in neighborhoods.

The new wrinkle in the Highpoint Initiative is the organized and swift offer of help to offenders who merit help, drawing in religious and other community leaders and social-service agencies.

Dennis Langley, president and chief executive officer of the Urban League of Rhode Island, said Providence was one of three cities asked to participate in the Highpoint Initiative because his chapter and Esserman are held in high esteem by his national organization. His chapter is taking responsibility for working with the seven minor offenders.

“We are not about arresting people,” Langley said at the formal announcement in the auditorium of the Public Safety Complex. “We are about changing communities and changing lives for the benefit of our society.”

Langley and police supervisors said they hope to dispel fear and reduce the feeling of disorder in certain neighborhoods by reducing or eliminating street dealing.

“Over the years we have had so many individuals complaining that we cannot live in our neighborhoods because of the drug trafficking,” Langley said.

Only time will tell, said police Lt. Thomas Verdi, commander of the city police Narcotics and Organized Crime Bureau, whether a program launched in the much smaller city of Highpoint, which is in a semirural region, can be successfully transplanted to larger cities with different demographics. Tucson and Kansas City also are trying it.

Lockwood Plaza and its immediate vicinity was chosen as the focus of the investigation, according to the police, because it was one of the more overt and busy drug markets and because the target area has numerous calls for police service. The target area is bounded by Broad, Myrtle and Dudley streets, Prairie Avenue and Stewart Street.

Thirty-three of those targeted are from in and around Lockwood Plaza, according to Esserman, which is a privately managed property of the Providence Housing Authority. The authority acquired Lockwood Plaza in a federal government foreclosure and spent $6 million to $7 million in renovations three years ago.

The housing authority tries to screen out prospective tenants with criminal records and has a longstanding policy of evicting tenants who are caught in drug-dealing or other serious crimes or who invite in relatives and friends who get involved in crime.

Although there was a target area, the probe spread citywide and arrests were made in a number of neighborhoods. Those arrested range in age from 14 to 49 years old. Most have been convicted of felony crimes and a majority are violators of their probation or parole, according to Verdi.

Nine of the suspects have been singled out for federal prosecution — the roundup was triggered last Wednesday, after a federal grand jury handed up their secret indictments — in large part because they were allegedly dealing in amounts of drugs that will subject them to harsher punishment in the federal system. The rest are to be prosecuted by the state, including the 27 not in custody but who are named in arrest warrants.

Among the nine to be prosecuted federally are Khalid Mason, 30, formerly of Pavilion Avenue, Providence, and Derrick Isom, 31, of Dunnell Avenue, Pawtucket, who are accused of running a crack house. They led a gang of street dealers in the Lockwood Plaza neighborhood, according to Verdi.

Mason, who had been named in a Providence police arrest warrant for at least two years, was caught by U.S. deputy marshals, living under an assumed name on the Mashantucket Pequot reservation in Ledyard, Conn. While a fugitive, according to Verdi, he had lived in California and Atlanta.

The nine are: Juan “Weezy” Forbes, 20, of Knight Street, Providence, who is charged with conspiracy to distribute and distribution of at least 50 grams of crack and with three counts of being a felon in possession of a firearm; Eric Grundy, 20, of Vandewater Street, Providence, charged with conspiracy to distribute at least 50 grams of crack and distributing crack; Daniel McClain, 28, of Stanwood Street, Providence, charged with conspiring with Grundy to distribute at least 50 grams of crack and distributing at least 50 grams of crack; Donnell Jenkins, 28, of Northup Street, Cranston, charged with two counts of distributing crack, one of which involves at least 5 grams.

Also, Ronald Hill, 35, of Broad Street, Providence, charged with two counts of distributing crack, one of which involves at least 5 grams; Fernell Brown, 20, of Knight Street, Providence, charged with two counts of distributing at least 5 grams of crack; and Isom and Mason, both of whom were charged with conspiracy to distribute at least 50 grams of crack, distributing at least 50 grams of crack, and using an apartment to traffic in crack.

Conviction of distributing or conspiring to distribute at least 50 grams of crack carries a maximum punishment of life in prison.

All except Grundy have been arraigned in U.S. District Court and pleaded not guilty and are being detained. Grundy is serving a state sentence and has not yet been arraigned.