The schools chancellor asks principals and parents to redouble their efforts to make sure the city's 1.1 million public school students are safe after a young gunman kills 17 people in a Florida high school. NY1's Lindsey Christ filed the following report:

Schools Chancellor Carmen Farina vows the city will redouble its efforts to prevent a mass shooting in city schools. That will include spreading a "see something, say something" message to encourage students, teachers and parents to be vigilant. 

"Words cannot describe when you hear about another tragedy in one of our schools. And to me, this is really a wake up call to the nation in terms of what are we going to do," she said.

Farina Thursday emailed all city public school principals and sent a letter home to parents, a day after a teenage gunman's deadly rampage in Florida.  She wrote that the Parkland high school shooting, which killed 17 students and teachers, "cut me to the core."

She told the principals they must rededicate themselves to making sure their buildings are safe. That means completing all required safety drills by March 15 -- a regimen of four lockdown and eight evacuation drills. 

In 2012, the Education Department adopted protocols guiding what city schools should do in certain emergencies, including mass shootings. If there is a known threat in the building, school officials are supposed to impose a "hard lockdown," requiring everyone, even unarmed NYPD school safety officers, to lock themselves into rooms, away from doors and windows, before police arrive. 

Now the chancellor is making clear that she wants schools to teach students what to look out for, and what to report, so that any potential warning signs of an attack are not missed. 

"We're asking particularly principals and teachers to talk to students about what might be something that they may want to in confidence let an adult know about. Because with all of the social media and other things out there, there are many ways of information getting out there and it's something we really need to supervise." 

The Chancellor also asked parents and teachers to talk with students about what happened - and to reassure them that the city is working to keep their schools safe. 

"In New York City we have done everything possible to mitigate that this doesn't happen in our schools," Farina said.

Her other message is that the country must reckon with why school shootings have become so common.  

"It's too normal and it's got to stop being normal, business as usual," she said.