When a gunman opened fire with an AR-15 at a large high school in south Florida, the 17 dead included students and school workers, young and old.

Here is a look at some of those who lost their lives in the deadly shooting at Marjory Stoneman Douglas High School. Not all the names have been publicly released.

AARON FEIS

Assistant football coach Aaron Feis was shot to death while selflessly shielding students from bullets. A tweet from the school football program ended: "He died a hero and he will forever be in our hearts and memories."

JOAQUIN OLIVER

Joaquin Oliver was known by his nickname "Guac," short for "guacamole," because many couldn’t pronounce his first name. "My friend will literally never get to say, "I graduated high school,'" said Tyra Hemans, a 19-year-old who said she has been friends with Oliver since they were freshmen.

CHRIS HIXON

A married father of two and the athletic director at Marjory Stoneman Douglas High School, Chris Hixon wasn’t shy about jumping in wherever he was needed, said friend and one-time colleague Dianne Sanzari.

Hixon belonged to a Roman Catholic church in Hollywood. The Archdiocese of Miami confirmed his death Thursday.

MEADOW POLLACK

Meadow Pollack's parents called her phone repeatedly only to hear it ring, as they kept an anxious vigil outside the hospital. But on Thursday, her father, Andrew Pollack, confirmed that his daughter was among the dead, the Palm Beach Post reported. Eighteen-year-old Pollack, a senior, had planned to attend Lynn University, her father said.

ALYSSA ALHADEFF

An amateur soccer club said one of its players, Alyssa Alhadeff, was among the students killed in the mass shooting at Marjory Stoneman Douglas High School.

Parkland Soccer Club posted on its Facebook page that Alhadeff was a "loved and well respected member of our club and community."

ALAINA PETTY

Fourteen-year-old Alaina Petty was among those who died in the shooting, great-aunt Claudette McMahon Joshi confirmed in a Facebook post. "There are no hashtags for moments like this, only sadness," she wrote, asking people to lift up Petty's family in prayer.

SCOTT BEIGEL

Students said geography teacher Scott Beigel, 35, helped them enter a locked classroom to avoid the gunman and paid for the brave act with his life. "If the shooter would have come into the room, I probably wouldn't be speaking to you now," student Kelsey Friend told Good Morning America.

JAIME GUTTENBERG

Ninth grader Jaime Guttenberg, 14, loved to dance and hoped to become an occupational therapist and mother, aunt Abbie Youkilis said. "She always looked out for the underdog and the bullied and she probably had been kind to the (former) student who shot her," Youkilis said in a written statement sent to The Associated Press.

MARTIN DUQUE ANGUIANO

Shooting victim Martin Duque was one of Isaac Briones' best friends. "He was like, one of the nicest people I knew," said Briones, 15. "He was so caring." Briones said he last saw Martin the day of the shooting during first period.

NICHOLAS DWORET

Nicholas Dworet, a senior, was killed in the shooting, the University of Indianapolis confirmed. Dworet was recruited for the university swim team and would have been an incoming freshman this fall. "Nick's death is a reminder that we are connected to the larger world, and when tragedy hits in places around the world, it oftentimes affects us at home," said Robert L. Manuel, University of Indianapolis president.

PETER WANG

Peter Wang was 15, and an ROTC student at the school.

Relatives said he wasn't interested in statud, but in helping others. A cousin told the Miami Herlad that Wang was last seen holding a door open so others could get away from the gunman.

ALEX SCHACTER

Alexander Schachter was 14, and a trombone and baritone player. His father wants to start a scholarship fund to help other "students experience the joys of music. He also wants to help fund increased security at schools.

HELENA RAMSAY

Helena Ramsay was 17. Although described as somewhat reserved and soft-spoken, she was relentless in her academic studies. One relative described her as brilliant and witty.

CARA LOUGHRAN

Cara Loughran was 14, and described as an excellent student who loved the beach and her cousins. An aunt wrote on Facebook that "while your thoughts are appreciated, I beg you to do something."

LUKE HOYER

Luke Hoyer was 15, described by an aunt as a sweet person who loved basketball and "smiled all the time."

GINA MONTALTO 

Gina Montalto was 14, and on the winter color guard squad. Her mother Jennifer posted this tribute on Facebook:

"She was a smart, loving, caring, and strong girl who brightened any room she entered. She will be missed by our family for all eternity."

CARMEN SCHENTRUP

Carmen Schentrup was 16, and one of 53 National Merit Scholarship Program semifinalists in Broward County. Classmates praised her for her intelligence. She wanted to go to the University of Washington.

Information from the Associated Press was used in this report.

Interactive timeline: Parkland shooting