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PARKLAND (CBSMiami) – Four weeks ago in Parkland, everything changed.

A man opened fire inside his former school, taking lives and injuring others, leaving many with deep emotional scars.

One month later, the unyielding heartache and pain is still apparent.

There have also been important questions raised about how law enforcement responded to the crisis.

The long term takeaway might be how this awful tragedy leaves a lasting imprint of positive change on the community.

It all began on Valentine’s day at 2:21 p.m.

That’s when the Broward Sheriff’s Office says 19-year-old Nikolas Cruz walked into the freshman building at Marjory Stoneman Douglas High School, took out an assault rifle and started firing.

School Resource Officer Scot Peterson was armed and on campus and the first to report what he heard.

He would later be criticized for not entering the school.

Cruz’s violence lasted about 6 minutes.

He’s accused of murdering 17 people and injuring 17 others.

He left the school with the mass of students, hoping to blend in.

After getting a drink at a nearby store, police arrested him a short distance away.

PHOTO GALLERY: National Walkout Day Across South Florida & The Nation

As Cruz appeared in court the next day, the shock over the unthinkable violence overflowed.

Memorials brought the community together to remember the students, teachers and coaches who died in the gunfire, lives of promise and hope cut short by bullets.

We also learned the stories of heroic teachers and students who saved lives.

Students from the school reacted to the shooting with outrage at gun laws that allowed Nikolas Cruz to purchase an assault rifle before he could buy a beer.

Their anger and action led to the Never Again movement.

The students and parents took their message to Tallahassee and some also met with President Trump in Washington D.C.

The community gathered for a CNN Town Hall to directly question elected officials about gun laws and how to prevent school shootings.

One memorable exchange came from Fred Guttenberg, whose daughter Jamie died in the attack.

“Your comments this week have been pathetically weak,” Guttenberg said to Sen. Marco Rubio at the town hall.

And the questions about Cruz got louder as people wondered about his history with the Broward school system.

We learned that the FBI and BSO received tips about Cruz’s behavior in the past few months yet the tips went nowhere.

Broward Sheriff Scott Israel also admitted that Deputy Peterson did not enter the building and Israel said he should have.

“What I saw was a deputy arrive at the west side of building 12, take up a position and he never went in,” Israel said in late February.

BSO radio transmissions reveal that just as the shooting ended, Peterson gave a specific command as Cruz left the building and the victims lay dead or dying inside.

“Broward, do not approach the 12 or 1300 building. Stay at least 500 feet away at this point,” Peterson told officers over dispatch on the day of the shooting.

Those decisions and the decisions of other first responders in those chaotic minutes of the shooting are the focus of several law enforcement investigations.

Two weeks after the violence, students returned to school with a massive memorial rising and plans to tear down the building where the violence unfolded.

As everyone tried to put their lives back together, the fight for gun control continued.

Florida Governor Rick Scott signed the Marjory Stoneman Douglas High School Public Safety Act, raising the age limit to buy assault rifles, banning bump stocks, adding a 3 day waiting period on gun purchases and adding more money for school security and mental health services.

The bill also added a controversial voluntary program to arm teachers, and the NRA filed a lawsuit over the bill showing just how challenging true change may be.

As the one month mark neared, the focus again to shifted to Cruz as a grand jury indicted him and prosecutors announced they would seek the death penalty.

A month later, people continue to visit the Parkland memorial.

A chance to share the grief of their neighbors and friends and pray for those whose lives were forever changed.

This is a community in need of healing.