Boston Police Commissioner William Evans says the biggest threat on Boston's streets is a vicious cycle of gang violence.

The violence "has no meaning, and really destroys the structure of the city," Evans said in an appearance on Boston Public Radio.

Evans' department had a bit of promising news last week, when it announced shootings and violent crime were down 12 percent in 2014 from the previous summer. That still meant there were 84 shootings and 10 deaths from guns over June, July and August. Evans said drastic actions can lower rates of violent crime even further in the city, but more needs to be done than just removing guns from the streets.

"We can take a million guns off the street, and a million guns are going to replace them. Unless you give kids opportunities it's not going to solve the problem," he said.

The commissioner stressed the need for officers to engage with communities they police — being role models for the community.

"It's going out there and speaking to them like our officers do. I look at [Aaron] Hernandez from the Patriots. He [was] making all the money in the world, but he couldn't break the allure of being in a gang and hanging with the kids."

Evans said there needs to be a complete shift in how kids think about belonging to gangs.

"There's a cultural change" needed so that kids are saying, "it's not cool to be in a gang, it's not cool to carry a gun."

Evans spoke about recent events in Ferguson, Missouri: the shooting death of Michael Brown, community meetings and mass protests, and even the shooting of a police officer.

"Unfortunately, when an incident like that happens in the United States, we all wear it," he said. "We all got painted with the wrong brush."

Police officers in Ferguson were reported to have covered up their badges with black tape as a sign of solidarity with Darren Wilson, the white officer who shot Michael Brown, a black 18-year-old. Evans said no such thing would happen in Boston.

"We have a clear policy" of officers wearing identification, Evans said. "I had a meeting this week with the ACLU. I assured them this is not our policy."

Evans said the likelihood of a similar incident happening in Boston was small.

"We have great diversity in our department, the most diverse command stats that we've ever had. So, I don't like to compare us to Ferguson." 

On Sunday, California Governor Jerry Brown signed a new law which requires consent — the law has been called "yes means yes" — before people engage in sexual activity. Jim Braude and Margery Eagan, cohosts of Boston Public Radio, asked Evans whether he thought the new law could make sense for Massachusetts, too.

"Having a daughter [who is] 24 years old, I like the new standard," Evans said.

He said it would be particularly helpful in investigating cases of sexual assault on college campuses in Boston, places where the BPD has run into some difficulty. 

"A lot of [universities] have their own police department. They control what gets to us and what doesn't. (...) You gotta let the Boston Police know" about sexual assault," he said.

Evans talked about Boston's recent designation as one of three pilot cities the Department of Justice will partner with to combat domestic terrorism. Evans said the program has been in the works for a while. "We had talked probably three months ago before the whole ISIS crisis started to really bloom here. We dealt with Carmen Ortiz — the US Attorney — when she chose Boston as one of the three sites," he said. "I think we were chosen because we have relationships already" between intelligence and on-the-ground assets, "and I think we're able to build on that."

Braude asked Evans whether the program could infringe on citizens' First Amendment rights. "People have a right to speak out against the United States," Evans said. It's only a concern when it rises to the level of "dangerous" or life-threatening speech, he said.

Eagan raised the prospect of militarized response to domestic threats — such as the one seen in Watertown after the Boston Marathon bombings — and whether tanks and advanced weaponry really keep citizens safe. "We have the capability if we have a 'Code 99' tactical situation, they bring out (...) the armored vehicle. [But] that's kept under wraps here in Boston," Evans said. "The first thing me and Mayor Walsh did was K.O. the idea of rifles in police vehicles."

Evans was especially sensitive about his department appearing overly militarized during the 2014 Boston Marathon, despite being on guard against another possible terror attack. "None of that stuff would be seen. I wanted that Marathon to be very much like April 15th of the tragedy, when people wouldn't be intimidated."

Evans said law enforcement's show of force during the Watertown manhunt surprised him. "It was frightening to me too, to see the tanks rolling around," he said. Evans added: "I agree that we have to tone it down. (...) You've seen the way that we dealt with Occupy [protestors]. (...) We don't show up anymore with the sticks and the helmets."

Commissioner Evans was asked whether he would consider putting cameras on police officers, the way officers in Los Angeles and Miami Beach are now doing. Evans was skeptical about the idea.

"We've had some discussions on it, [but] we have a strong union here. It's something we'd have to do with the unions," he said. "I don't see us having a problem right now that we'd have to go to that," Evans added. He said there are privacy concerns that haven't been addressed. "Are we going to be able to film inside someone's private residence? How long can you keep that video footage? [What about] the costs? (...) There's a lot of issues that we have to work out," Evans said.

Braude asked the Commissioner how he keeps his head level with such a busy schedule. Evans' answer: running. "That's the most important thing in my life — besides my wife and three kids, they'd kill me if I said that! It's more mental than physical."