For years, the gangs have plagued the Lenox Street Housing Development. The hallways are crowded with men smoking marijuana and many residents can point to the spots where young people have been shot and killed.

“There’s been death after death after death,’’ said one woman, smoking a cigarette just feet from where a young woman was murdered in her car in 2014.

Before dawn Thursday, law enforcement officials swept through the Lower Roxbury complex of low-slung buildings, arresting 19 alleged gang members who they believe control most of the area’s violent drug trafficking. Eight more were being sought Thursday evening.

In the hours after the raids, residents expressed joy and relief — though all spoke on condition of anonymity, saying they feared retribution.

“It’s a very good day for the law-abiding residents of Lenox Street,’’ said Bill McGonagle, head of the Boston Housing Authority.

Thursday’s raid followed a more than yearlong investigation by federal agents, Boston police, and Boston Housing Authority officials, according to an affidavit filed in federal court, and involved a cooperating witness who bought drugs and guns.

“These defendants bring violence, fear, and intimidation to a community in the heart of this city,’’ US Attorney Carmen M. Ortiz said in a statement. “Lenox Street’s residents, surrounded by illegal activity and the violence that accompanies it, are made to feel like prisoners in their own homes.’’

The development, which police say is home base for the Lenox Street Cardinals gang, was one of the city’s 10 “hot spots’’ for violence in 2015, according to the affidavit. Between March 2012 and June 2015, there were 30 shootings and more than 75 reports of shots fired, and the development led the Boston Police Department’s District Four, which includes parts of Roxbury, Fenway, the Back Bay and South End, in shootings, shots fired, robberies, and firearm and drug arrests from 2014 to 2015. Nearby Ramsay Park was associated with open-air drug markets, the affidavit said.

Most of those charged Thursday were allegedly members of Lenox Street Cardinals, or of allied gangs including the Villa Victoria Pirates, and many had long and violent criminal records.

Of the 19 people charged federally, 11 have been previously shot or stabbed or both, according to the affidavit — including one man who had been shot 23 times. During the investigation, the affidavit said, two of the targets were shot and a third was murdered — all in the area of the development.

“It’s rough, it’s really rough — as far as I’m concerned, [police] need to be here every day,’’ said one man as he cut through a courtyard. “In eight years, I’ve probably seen a good three or four people get killed.’’

One woman said that in six years, she has seen at least five shootings, including one homicide. Her neighbors openly sell crack, she said, and addicts come through her building urinating, spitting, and performing sex acts in the hallways in exchange for drugs.

The woman who spoke while smoking her cigarette said that gunfire was so typical that neither the shooters nor the bystanders bothered to hide for long after shots rang out.

“It’s a normal routine,’’ she said. “They shoot, you grab your kids, and two minutes later, everybody’s outside again.’’

Within a roughly 100-yard radius, she said, two people including the woman in her car had been killed, two people overdosed and died, and another person was shot in a hallway.

Another resident who asked to be identified as “Nestle’’ said she never walks through the center of the development because it was where gang members congregated.

“I just mind my business,’’ she said. “You know but you don’t know. See but not see.’’

Her best trick to ensure she is left alone: She talks loudly to herself.

“People think you’re crazy,’’ she said.

The development has been the subject of at least two other law enforcement operations aimed at clearing out the drug dealers, according to the affidavit: one in 2011, which resulted in 21 arrests, and another in 2012, which resulted in Lenox Street, Villa Victoria, and Annunciation Road gang members being charged with drug and firearm offenses.

Boston Police Commissioner William B. Evans commended investigators on Thursday’s raid, saying in a statement that the arrests “send a strong message that illegal drugs and guns have no place on the streets of Boston.’’

McGonagle, the BHA administrator, said he expected the sweep would have a “significant impact’’ on the quality of life of residents. In addition to the arrests, he said, those charged or linked to the case will be evicted.

“The children and families who live at the Lenox Street Housing Development deserve a safe, healthy environment free of the violence that goes hand in hand with the drug trade,’’ said Suffolk District Attorney Daniel F. Conley in a statement. “Local, state, and federal authorities will never waver in our commitment to those families and their right to live free of fear.’’

Officials are still searching for the remaining alleged gang members who were charged. Some of those arrested Thursday appeared in federal and district court.

Evan Allen can be reached at evan.allen@globe.com. Follow her on Twitter @evanmallen.