Mayor Muriel E. Bowser, front, and D.C. Police Chief Cathy L. Lanier, right, speak about the city's illegal guns and gun violence at police headquarters on Tuesday. (Jahi Chikwendiu/The Washington Post)

The District’s mayor and police chief on Tuesday urged tighter scrutiny of the legal processes that return repeat gun offenders to city streets — and to repeated rounds of violence — as the leaders confronted yet another raft of shootings over the holiday weekend that resulted in the death of one man and the wounding of seven others.

The call for heightened attention to how police, courts, prosecutors and probation agents handle gun offenders with previous convictions or run-ins with the law is the latest focus for city officials trying to explain the alarming rise in homicides this year.

Mayor Muriel E. Bowser (D) highlighted a case in which a man wanted in a shooting on a Metrobus last month had spent four months behind bars after admitting that he shot two youths in the legs in February.

Police Chief Cathy L. Lanier said more than half of the suspects arrested in this year’s homicides had prior gun arrests in the District, up from 27 percent last year. She also said that 21 homicide suspects and 26 homicide victims were under court supervision, such as probation, at the time of the killings, and that six homicide victims and 10 homicide suspects had faced prior charges in killings.

Noting that 14 of 24 people arrested in 34 gun seizures last week had prior weapons-related arrests, Lanier said, “To take guns off the same person over and over and over again is just unacceptable.”

Recently seized guns are displayed as Mayor Muriel E. Bowser and D.C. Police Chief Cathy L. Lanier speak about the city's illegal guns and gun violence on Tuesday. (Jahi Chikwendiu/The Washington Post)

Police said they have seized more than 1,100 guns this year, including 83 between Aug. 28 and Tuesday.

The Labor Day shootings began shortly before 10 p.m. Monday, police said, when gunmen opened fire in the 2900 block of Martin Luther King Jr. Avenue SE, a commercial strip near the new headquarters for the U.S. Coast Guard and the city’s new homeland security headquarters.

More than a dozen shots were fired, according to police, who listed victims suffering from gunshot wounds to the legs, buttocks, back and hip. All the victims were men, and the injuries were described as minor to serious.

About a half-hour later and two miles away, police said, two men were shot inside a home on Forrester Street SW, just off South Capitol Street, in the Bellevue neighborhood near Blue Plains. Police said one man was critically injured and a second victim was pronounced dead at the scene. The man killed was identified as Jarrell Hall, 28, of Southwest. Authorities did not release any other details about the incident.

Hall was the District’s 109th homicide victim of 2015, compared with 74 at this time last year, a 47 percent increase. There were 105 homicides in all of 2014.

Another man later was shot and wounded about 4:20 a.m. Tuesday in the 5200 block of Nannie Helen Burroughs Avenue NE.

The last time the District exceeded 109 killings was 2010, when 132 were recorded.

Bowser and Lanier spoke Tuesday at police headquarters, flanked by two tables lined with dozens of recently seized guns — from a pink .22-caliber revolver to what resembled an assault weapon. They spoke before attending the monthly meeting of GunStat, a law enforcement group that tracks gun offenders to develop crime-fighting strategies and identify likely future offenders to closely monitor. The District’s acting U.S. attorney Vincent H. Cohen Jr. also attended the GunStat session.

Bowser called attention to Bijon Lamont Brown, 20, who is being sought by Metro Transit Police in the Aug. 21 shooting on a Metrobus in the 2400 block of Elvans Road SE. A passenger, described by police as a bystander, was wounded. Brown is charged in a warrant with unlawful possession of a firearm.

Brown had been charged in March with assault with a dangerous weapon in the shooting of two youths in their legs on a basketball court in Southeast. He accepted a deal, according to court records, and pleaded guilty to attempted assault with a dangerous weapon. He was sentenced to six months in prison, a term that was suspended in July after he had served four months. He was then put on one-year probation.

A D.C. police arrest affidavit says Brown said that he shot at the two youths but that he didn’t mean to hit them. His attorney did not return calls seeking comment.

Bowser said of Brown, “We want to especially follow what his experience has been in the criminal justice system.”

Lanier and Bowser said they do not intend to criticize other agencies but want to identify whether problems fall with police, lawmakers, prosecutors or probation officers.

“Instead of seeing where else there’s blame, we’re looking to see where there are gaps in the system,” Lanier said.

But a statement from prosecutors highlights the complexities in many of these cases.

Bill Miller, a spokesman for the U.S. attorney’s office, said Brown’s case underwent a “comprehensive review,” but moving forward “presented significant legal challenges, including police investigative work, that made this plea the best possible outcome.” He also said that Brown had no prior convictions and had accepted responsibility and that the victims did not cooperate.