Mayor Stephanie Rawlings-Blake said Wednesday "most of the violence" in Baltimore is being fueled by gangs, including an internal power struggle within the Black Guerrilla Family gang.
"Violence is like an infectious disease: It is contagious, and you have retaliations," Rawlings-Blake told reporters at a weekly news conference.
The mayor said both the Police Department and federal agencies are investigating incidents related to the BGF. More than 25 people have been shot and about a dozen killed in Baltimore in less than a week.
The violence has continued since May when 42 people were killed, making it the deadliest month in 25 years.
"We took several members of the BGF leadership off the streets," Rawlings-Blake said. "There is clearly an internal fight between that organization, which is extremely violent."
Police attributed 2013's violence spike to the BGF gang, but talk of gangs had been relatively muted since then.
In June, authorities announced the federal indictment of several reputed BGF members, including the alleged citywide commander, Timothy Michael Gray, who court records show was arrested in North Carolina.
Rawlings-Blake also was asked to address Tuesday's announcement that officials had suspended the Safe Streets anti-violence program in East Baltimore. Officers found drugs and seven guns stashed inside the group's Monument Street office.
Two employees have been arrested.
Safe Streets relies on ex-felons to help bring down crime. It has been operating in four neighborhoods. It is administered through the city's Health Department.
Rawlings-Blake said she remains committed to the program. She said officials are looking at ways to "tighten up the screening process" as well as improving the ways the ex-offenders are monitored.
"Safe Streets has had challenges before in Baltimore and around the country," she said. "Any time you have a an initiative that depends on working with ex-offenders as the key to the program's success, you run the risk of some people who present as being out of the game who actually aren't."
Rawlings-Blake said the city's Health Commissioner Dr. Leana Wen is working to "ensure the workers we have in the program are actually reformed and want to see better for their communities."
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The mayor said the experience reaffirms her earlier position about using caution to expand the Safe Streets program. She said some have asked, "Why not just give it more money, just expand the program."
"It's not as easy as just flipping a switch," she said. "You have to have the right community organization to host the work and you have to have the right workers.