Andrea Castilla and her three siblings were raised by a single father. Her mother died of cancer when she was a teenager. 
One of her soccer teammates, Carol Avella, remembers Castilla for her bubbly personality. During a match in their freshman year, the Estancia team was soundly defeated by their rival school, Costa Mesa High School. She recalls everyone being mad when the game was over: 
Everyone on our team was mad [...] I remember telling Andrea she could have been a better defense and all she did was laugh at me. She said, ‘Carol, it’s just a game,’ and smiled at me. While the rest of the team was upset, she was cheering us up.
Andrea Castilla was in Las Vegas, Nevada celebrating her 28th birthday. She was attending a Jason Aldean concert during the Route 91 Harvest music festival when she was shot by Stephen Paddock in the Mandalay Bay Resort mass shooting. She was one of 59 dead and one of over 500 victims overall. 
After she was shot, her boyfriend, her sister Athena, and Athena's boyfriend carried her over a fence and stopped a passing motorist on a highway. The driver took them to a hospital in the back of his truck. 
She passed away almost immediately after reaching the hospital. However, her loved ones wait in the emergency room for seven hours after hospital staff confused her with another patient and told them she was in surgery.