(CNN) Two women who met decades ago both went on to become librarians at schools that have become household names because of deadly mass shootings.

Yvonne Cech worked at Sandy Hook Elementary in Newtown, Connecticut, when a gunman killed 20 children and six adults. Diana Haneski became a librarian at Marjory Stoneman Douglas High School in Parkland, Florida, where a gunman killed 17 people.

When the school shooting began in Parkland, Florida, Haneski immediately thought of all the things her friend Cech had told her over the years.

In an interview with CNN's Anderson Cooper on "AC360," Haneski said Cech had told her she needed to "make sure you have your keys on your person, your phone, your walkie-talkie. Those things were very important."

"I was trying to be ready, but I didn't think it would be getting ready for this," Haneski said.

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