After the weather turned warm, the bullets started to fly in some of Boston’s most violent neighborhoods, amounting to 28 murders this year, slightly more than in the same period in 2016.

Boston police have solved 15 of those homicides, and made arrests in five other murders from 2016, making for a clearance rate of 74 percent so far this year, officials said Tuesday.

Some homicides took a week or two to solve, while others took a month or more, police said. And in a rare instance, within minutes of the fatal shooting last week of a beloved hardware store owner, Boston police arrested three men they say were responsible.

Lieutenant Detective Darrin P. Greeley, commander of the Boston Police Homicide Unit, credits the resolve of investigators to solve the city’s most violent crimes.

“It’s a lot of great work from the men and women in the department who never give up,’’ Greeley said Tuesday during an interview at police headquarters. “We’re trying to send a message and hold those accountable. Eventually we will make the arrest.’’

At least three homicide cases are currently being presented before a grand jury, he said. And Police Commissioner William B. Evans said there is a warrant for the arrest of Desmond Tahatdil, 55, who is accused of killing his son, Brendan Tahatdil, 35, in March.

By the end of 2016, Boston police reported a 63 percent clearance rate for homicides that year, up slightly from a 61 percent clearance rate for homicides in 2015.

More resources and changes to investigative practices have led to this year’s improved clearance rates, Greeley said.

In the last several years, the homicide unit expanded to include 40 detectives, allowing the department to put more resources toward solving cases. Detectives are able to gather surveillance videos and other evidence, and interview more witnesses, he said.

In some homicides this year, suspects were captured on video surveillance committing brazen acts of violence, sometimes in the middle of the day. The footage helped lead to speedy arrests.

It took detectives less than 24 hours to arrest 15-year-old McKinley Archie for stabbing 18-year-old Anthony Woodbridge to death on Warren Street near Dudley Square Station shortly before 10 a.m. on July 7.

Information from witnesses also helped investigators to solve that case, Evans said.

“The community has helped us and stepped up,’’ Evans said.

Since homicides often occur outdoors and involve firearms, surveillance video from local businesses and information from witnesses have also helped solve cases, Suffolk District Attorney Daniel F. Conley said.

“We’ve had a good rate of more witnesses stepping up,’’ Conley said by telephone. “So many more people and businesses are investing in surveillance and equipment, [officials] are able to capture some of these events as they unfold.’’

Greeley said police understand that some witnesses may be reticent to supply information out of concern for their safety. But the district attorney’s office helps to protect witnesses to homicide, and police will meet people where they are most comfortable speaking, he said.

Still, homicides are up by five this year compared with the same period last year. The number includes one that occurred in 2016, but was determined to be a homicide in 2017.

Police officials said the recent spike in violence was largely the result of gang disputes. At least three murders were committed during the course of a robbery — two doctors inside of their South Boston home in May, and Andres Cruz inside his Mission Hill hardware store last week.

“We’re going to work hard to get guns off the street,’’ Evans said. “We’re working hard so that these kids don’t have guns and don’t pull the trigger.’’

Greeley said he expects that more of the homicides will be cleared.

“They’re all our kids,’’ Greeley said of the victims. “That’s the bottom line.’’

Evans said he’d like to see improvements in the number of arrests made in nonfatal shootings. As of Sunday, 122 people have been shot in Boston and survived, up by 27 percent compared to the same period in 2016. Most are gang-related and challenging to solve, he said.

“We don’t get the cooperation from victims,’’ Evans said. “Victims will tell us to go ‘fly a kite,’ and that’s frustrating.’’

Jan Ransom can be reached at jan.ransom@globe.com. Follow her on Twitter @Jan_Ransom.