America's sorrow captured in three cities

(CNN)First, it was Alton. Next, Philando. Then, five police officers.

Baton Rouge, Falcon Heights and Dallas now share a tragic connection -- one that's driving a tense undercurrent felt in every American city after days of violence.
The past three days have struck a nerve, and it's one that echoes some of this country's darkest times. Americans are asking: How can this be happening in 2016? When will this stop? What are the solutions?
And ... Why?
    The answer to that one word may be the most painful. And it's one that, on Friday night, people in these three cities are grappling with -- from protesters, to police, to neighbors, to families.

    In Dallas

    In front of the police headquarters in Dallas, handfuls of people solemnly trickle in and out. They've come to pay their respects.
    Some salute the two cars placed out front in honor of the fallen. Others reverently touch their doors and windows. One says the Lord's Prayer. A black man, his daughter by his side, embraces a white cop.
    "They'll never come home," said Jared Pereira, whose friends and family served on this force. "How do you explain that to their children? To prevent violence you create more violence?"
    Micah Xavier Johnson, the man who killed five police officers at a demonstration Thursday night, told authorities that he wanted to kill white people, that he was upset about the recent shootings.

    "We need more dialogue and less action." - Jared Pereira

    It's stifling in Dallas. Some of the officers in uniform hand out water as the blistering sun begins to set. At times, a brief gust of wind blows flowers or handwritten notes off the makeshift memorial. It doesn't take long for someone in the crowd to pick them back up.
    As a mother and her two children walk by, the 6-year-old girl points to a memorial of candles and stuffed animals. "Mommy, why are these here?"
    She's asking the same question the adults are asking.
    Nearly 24 hours after shots rang out here, it's stunned silence.
    Then, a small choir breaks the melancholy quiet.

    Singing together for peace outside police HQ #dallas

    A video posted by mallory_simon (@mallory_simon) on

    In Baton Rouge

    Meanwhile, more than 400 miles from Dallas, people in Louisiana are trying to do what they do best: in darkest times, they celebrate life.
    At the scene where Alton Sterling was shot this week, a DJ in a tent plays R&B and black revolutionary tracks. There are no cops in sight. If you didn't know what happened here this week, you'd think it was a block party.

    "This happens too much. Oftentimes, the police come out to provoke. Is it fear embedded in them? Part of their training? Or something they've carried with them all their lives?" - Clabon Lacy, 61, Baton Rouge

    Kevin Thomas, a 47-year-old black man, stands outside the convenience store on this muggy evening. He lost a cousin to an overdose Monday. On Tuesday, his friend Alton was gunned down.
    "When I woke up this morning and saw the news about the police officers in Dallas, I cried," he said. "We're one of the strongest and weakest countries in the world."

    "We need to get shoulder to shoulder, hand to hand, black and white and come together." - Dianna Marshall, 26

    At a nearby furniture store, Zack Fields, 25, talks with Belafonte Anderson, 55, a therapist and mortician.
    Fields is white. Anderson is black.
    "You can't keep oppressing people, whether they're Asian, Hispanic or whatever," said Anderson, chomping on a cigar. "When nothing changes, the pressure keeps building up."
    Lines of communication need to be opened, especially in deeply segregated cities such as Baton Rouge.
    "There's this side of town and the other side of town and they're split racially and economically," Anderson said.
    "We've had 75 murders in Baton Rouge this year, and most were in this side of town. Where are the protests for those lives?" Fields asked.
    Dana Winbush, 40, tried to keep cool standing under the furniture store's awning. She held a plastic foam cup topped with ice in one hand, a protest sign in the other.
    "In this neighborhood, these protests are ineffective," she said. "The people who need to see them don't even drive around here."

    "You have to understand, people get tired. We've been oppressed, depressed. There is ignorance on both sides." - Keiana Jones, 33

    Dallas, she said, "changes the dynamics" even more.
    "Now they have a reason to kill us," she said. "It will make matters worse."
    Just across the street, Meg O'Connor, a 24-year-old white college student, stood over a handicapped parking spot, looking down at a memorial built for Sterling.
    "I've been surprised by how normal people outside of this community are going about their normal lives," she said. "It was when driving into this neighborhood that I felt the first tangible sense of grief and emotion in this city."

    In Falcon Heights

    On the sidewalks of Falcon Heights, where Philando Castile was shot and killed, the concrete is covered in chalk. Where blood was spilled are now scribbled messages, seemingly written for Castile or a higher power.

    Chalk messages left for #philandocastile at the shooting scene. More on @CNN

    A photo posted by Rosa Flores (@rosaflorescnn) on

    "We didn't know you but we are so sorry."
    "Lord let him be the last. May he not die in vain! Peace to all!"
    "Your life means something."
    Though Thursday night's ambush in Dallas occurred during a protest partly inspired by Castile's death, it "was not because of something that transpired in Minnesota," says Diamond Reynolds, Castile's fiancée who started a live stream on Facebook after he was shot by a police officer.
    "This is bigger than Philando. This is bigger than Trayvon Martin. This is bigger than Sandra Bland," Reynolds said. "This is bigger than all of us."