Word of a shooting, with few details and much speculation. An hours-long wait, only to be told their loved one wasn't coming. A coffin in the cargo hold of an airplane.

For more than a week, this has been a grim reality for many of the family and friends of 58 concertgoers killed on the Las Vegas Strip in the deadliest mass shooting in modern U.S. history. And nearly five years ago, 2,500 miles away in Newtown, Conn., it was real, too, for the parents of 6- and 7-year-old schoolchildren.

One of those parents was Alissa Parker. She recalled that pain Tuesday morning as she spoke to about 250 Delaware County first responders, school administrators, and teachers at the district attorney's safe schools summit — all the more important, officials said, in the days after the Las Vegas tragedy.

"It is never easy for me to do this," Parker said. But "I promised myself that I'd do whatever it took to make sure no one else would become me."

Her 6-year-old daughter, Emilie, an artistic and thoughtful first grader with her mother's blond hair, was killed at Sandy Hook Elementary School on Dec. 14, 2012, when a gunman entered the school and fatally shot 20 children and six adults in five minutes.

To honor her daughter, Parker has become an advocate for school safety. She cofounded Safe and Sound Schools, a nonprofit dedicated to emergency prevention and preparedness.

Parker told a rapt audience at Drexel Hill's Drexelbrook event center that she was shopping for Lego bricks — a Christmas present for Emilie — when she was notified of a shooting at an unnamed school.

As Parker drove to Sandy Hook, she thought back to her most recent parent-teacher conference.

Visitors had to be buzzed into the building, Parker said, but she recalled thinking how easy it would be to circumvent that system. Once inside, there were no barriers between visitors and a line of classrooms, she said.

Parker had pondered that for a minute when she entered the lobby for her conference, she said, but then "turned the corner and walked the three classrooms down to my daughter's room."

Parker and her husband, Robbie, also discussed that classroom doors did not lock from the inside.

On the day of the shooting, teachers in the front hallway would have had to leave their classroom to lock the doors, risking their lives and drawing attention to students. Her daughter's teacher that morning was a substitute, Parker said, and didn't even have the key to her room.

Parker implored school officials to think about how many locked doors and barriers would come between an intruder and their students. And to responders, she stressed that in a crisis, "the words that you use matter."

At the firehouse across from the school, which became a makeshift command center, parents became frustrated.

"They didn't know what to say to us," Parker said. "They would have this blank stare when we'd ask definitive questions: 'What happened to our kids? Are they dead?' "

At one point, Connecticut Gov. Dannel P. Malloy spoke, unaware that the parents did not know — officially — that their children were gone. Someone asked: What happened to children who were taken to the hospital?

Malloy replied, according to Parker, "Those children have since expired."

The governor has said he struggled to find the right words in that moment.

In the years since the shooting, Parker has become a proponent of finding hope after tragedy. She has said publicly that she forgives her daughter's killer. And throughout her speech Tuesday, she pointed out bright spots.

She recalled how firefighters attempted to shield her and her husband from news cameras as they walked out of the firehouse that day without their daughter. And remembered that when Emilie's body was flown back to the family's native Utah to be buried, the plane's crew unloaded the coffin by itself, placing cards and gifts in its path.

"There was hope," Parker said. "There was goodness that outweighed the darkness."

Delaware County District Attorney John J. Whelan  stressed that all county schools have a button that would alert law enforcement of an intruder with a weapon and send officers in seconds.

Officials vowed to keep working to make children safer.

"When we send our students to school in the morning," Delaware County Councilman David J. White said, "we want to know they're coming home."