I can't find any grammatical errors, but I think the story could be more exciting, although it is written nicely.

*** The story is coming along nicely...but...."the suspense is killing me"!!! You sure do like to leave em hanging huh? Thats good, thats very good...but do it to the others not to me...LOL! All kidding aside, it really is coming along nicely, great visuals, great dialoque...great writing. I know if I ever need assistance writing something suspenseful I know who I am going to... I was recently challenged by my own daughter to write a thiller/romance and I wonder if could get some help with some of the scenes...maybe you can help? The story has wonderful potential as a novel, I hope that that is the plan for this particular piece... I wait with bated breath for the next chapter. Don't make me wait too long, I may turn a lovely shade of blue...LOL! Write on...***

Across the street Jake sat, peering out the front window while his brother Kyle lay on the couch reading and listening to the new album by Van Halen with headphones on. The two brothers and their indolent mother had been up for hours. Kyle had already made them all breakfast, serving his mother’s in bed. Something he always did. He had gotten his brother dressed and cleaned up after an early morning fit. This was the first time Kyle had had the chance to relax after an already exhausting morning and he was just glad his brother was content enough in the moment to allow it.

This paragraph can be focused so the experience is lived through Kyle. It might even be two paragraphs. The opening line, "Across the street Jake sat peering out the front window..." made me think the paragraph was going to be about Jake.

From start to finish Jake sporadically gave a commentary of the events out the window from across the street in his own special way without much regard from the older sibling.

Your dialogue following this, where you show Jake doing it, works better. I think this sentence tells it to us before it happens, so it feels "explainy."

With a childlike tilt of the head Jake looked from window to an oblivious Kyle. When no reaction signifying that he was correct in his guess of right or wrong came from his brother he again returned his gaze outside like it was no big deal. There were two loud bangs across the street from shots being fired.

Again, I think it can be more from Kyle's experience. I think this would benefit from a narrative voice 3PL from Kyle. That might pull the reader into the experience faster.

About six more minutes went by. Jake quietly listened to the yelling and screaming outside as more and more neighbors gathered in what was becoming a circus of events.

"six minutes" - who is counting the minutes? "Moments" would avoid this.

Also, when you say "Jake...listened..." it automatically assigns a 3PL to Jake, because one can't really observe someone listening. "Listen" is an experiential verb, so the reader then assumes a 3PL of Jake.

Someone had obviously called 911 which set into motion an any case scenario which called into action every emergency vehicle in the county.

Who's thinking this?

This time something else in the mess of things caught his eye. Nonchalantly, Jake got up and went out the front door without looking back.

Again a 3PL of Jake.

Meanwhile, Kyle, absorbed in the music, was on stage on his knees, leaning back and jamming with an electric guitar next to Eddie Van Halen. His hair was frizzed out and bounced back and forth as he jammed his head to with the rhythm of the music. Women in the front row were jumping up and down, waving their arms and screaming and crying at his mere smile and a wink. As the song, I’ll wait ended he looked back and Alex on Drums gave him a thumbs up. David Lee Roth strutted by and smacked his hand saying good job.

This scene felt a bit comical to me. From what I recall of Kyle, he's a serious, strong-hearted empathetic character. It just surprised me to see him so loose, and it made me wonder what his characterization really is.

Instinct suddenly brought Kyle back to reality

This was just a tad too passive-voice for me...

Just like a child Jake would quickly get into trouble without constant supervision.

This line felt "telly"

In route something outside the living room’s front window caught his attention in the corner of his eye so he backtracked a few steps.

I think shortening this sentence would help me realize better the point is that he noticed something outside his window.

Then amongst it all he caught a glimpse of his brother, unnoticed by everyone on the scene, climbing aboard the fire engine. “Oh, shit!” He repeated and bolted out the door. He allowed himself to take in the scene a bit as he quickly headed toward it. He had never seen such a gathering of forces in all his life so it was a bit eerie seeing all this here, this close to home. He fancied a few scenarios that all came to the same conclusion. The girl that lived there must have been the cause.

brother...climbing aboard the fire engine - that's PANIC! And "oh shit" sounds about right.

But then he "takes in the scene" and realizes he'd "never seen such a gathering." While all that might be true, I feel the "oh shit" vibe should continue until he resolves his panic. Short sentences following Kyle out running to the fire engine. Then when he reaches Jake, he can finally "take in the scene" and notice "the gathering"

Words came to mind, left over from last night, of what he would liked to have continued to say to her but instead he gave way to curiosity.

This thought-stream felt a bit clunky to me.

Kyle sighed and looked toward his brother. “Don’t apologize to me. Apologize to him.”

Still seems like kind of a mean thing to say, despite it all. I wouldn't like Kyle as much if he was so snippy and defensive.

Montana walked over to the window. She glanced out to see her father in the police car cussing up a storm. Her mother, still in her nightgown talked with police with a dazed look on her face. Immediately, she backed away. This is what she caused. She was always causing shit. She almost got to the point where she felt bad for herself but quickly discarded the emotion, thinking to herself out loud. Fuck them. She turned to Jake who was now looking at her with an innocence. Normally it wasn’t easy for her to admit she was wrong but everything around her in the moment made it all easier.

This switches perspective to Montana (3PL).

“You can tell a lot about a person by the music they listen to.” She said, more or less just speaking out loud. “A wanna be like everyone else.” “What kind of music do you listen to.” Shamus asked. Montana walked back to the window. All was now clear outside. “I like The Clash, Sex Pistols. Stuff like that.” “Very punk of you.” Shamus snorted, “Figures.” She turned, looking him up and down as if to size him up. “I suppose you like gracious melodies from the likes of Wham and Boy George then.” She said in her best sarcastic voice. “Damn, your good.” he said, lowering and shaking his head. “At what.” She retorted as if losing her patience. “At being a bitch.” He spoke matter of fact. At this Montana batted her eyes and smiled a coy smile. “Thank you,” she said, turning on her heel.

This dialogue didn't  seem to me to amount to much character or plot development. I do think that we need a little more plot development to keep readers intrigued to move on.

I hope my notes on this project have been helpful. I think you've got some well written elements. My major concern is with POV shifting. Ultimately it will be up to you as to what you feel is best in handling that. I really liked certain moments in Chapter 1 and 2. Chapter 3 is much shorter, and (I feel) lacked some of those intrinsic moments I felt were effective earlier, such as the walking-down-the-steps moment, when Montana realizes her father is letting his food go cold, the initial sequence between Kyle and Montana when she discovers Jake is autistic. Those worked quite well. But I felt less happened in Chapter 3. It tells us some things that came after Chapter 2, but doesn't seem to introduce anything new.

Anyway, I hope you keep it up and I wish you the best of luck!