There are over 100,000 public schools in the US.  Each have multiple doors and many have a completely open site layout with dozens of classrooms with exterior facing doors.  It would require millions of armed security which makes it neither the quickest nor most pragmatic solution.  That would easily cost over $50 billion per year (1 million officers @ $50k per year).  We just cut taxes.  Good luck getting funding.

And let's not forget that many schools already have security and it still doesn't seem to stop them.  Marjory Stoneman Douglas HS in Parkland, FL had one.  Great Mills HS in Maryland had one and he shot an innocent student.

And this one, Santa Fe HS in Texas, had a school officer...the suspect shot him.

There are over 100,000 public schools in the US.  Each have multiple doors and many have a completely open site layout with dozens of classrooms with exterior facing doors.  It would require millions of armed security which makes it neither the quickest nor most pragmatic solution.  That would easily cost over $50 billion per year (1 million officers @ $50k per year).  We just cut taxes.  Good luck getting funding.

And let's not forget that many schools already have security and it still doesn't seem to stop them.  Marjory Stoneman Douglas HS in Parkland, FL had one.  Great Mills HS in Maryland had one and he shot an innocent student.

And this one, Santa Fe HS in Texas, had a school officer...the suspect shot him.

If therse 10 kids dead and a couple of teachers..... no offense but what good is "thoughts and prayers" gonna do for the dead?

It seems like every month in the USA theres another episode like this.
At some point something had to be done about the gun issue in the US.... youd think? right?

And place a minfield on the schoolyard and give each student a map to memorize. That will limit the number of potential shooters to students who go to the same school.

As for "we already have common sense gunlaws" you have the most insane and lax gunlaws of any first world country.
There is no common sense in restricting background checks when 97% of the population wants universal background checks. http://theweek.com/speedreads/756459/97-percent-americans-want-universal-background-checks-gun-buyers-67-percent-want-ban-assault-weapons
There is no common sense that you require no safety training to own a firearm when 495 people died in the US in 2016 from just accidentally discharging a firearm. https://www.aftermath.com/content/accidental-shooting-deaths-statistics

495 people! To put into perspective, it would take about 55 years for Japan to have as many gun related deaths in total (including suicide, homicide, police shootings and accidents) if Japan had the same population as USA. (They have about 30% of the US population.)
And just for the record, USA had 33,599 gun related deaths in total that year. (Although most were suicides. But the homicide rate is still astronomical.)

And there is no common sense in gun laws that produce more guns in circulation than there are people in the country. The black market definitely contributes to that, but so do your gun laws and gun culture mentality.

Your gun laws are not even close to common sense. Everyone who owns a firearm should have to go through mandatory safety training, just like you do for operating a vehicle. And there should be universal background checks on gun purchases, so that people with a history of violence or severe mental illness don't get their hands on guns.
Your laws even let the Orlando club shooter buy assault rifles, while he was put on a no-fly list for suspicion of terrorist group affiliations on two separate occasions.
That's grounds for preventing him from flying, but not buying guns?

Yeah, common sense my ass.