Alejandra Rojas still can't believe the boy she went to high school with is gone. "You don't expect anything like this to happen so close to home, and especially to one of your friends," Rojas said. Adrian Balleza, 29, was among those killed Wednesday morning at the San Jose VTA rail yard shooting. "Adrian just had a baby, he just got married, he has a beautiful wife," added Rojas. "He had so many friends that love him and who will always love him."Hundreds of people gathered Thursday evening at San Jose City Hall for a vigil that began at 6 p.m. Flowers were presented at a growing memorial on East Santa Clara Street."Now, there's also a mass suffering that just took place. And it's gonna continue to take place for a long time," said Kevin Ng, who said his sister went to high school with Balleza. "I felt bad that when I was getting up for work and just getting ready, starting my meetings, people were dying," said Jaspreet Kaloti. "Someone chose to bring a gun to work and shoot innocent people."For some at the vigil, Wednesday's deadly attack raised the question of what it will take for the violence to end. A database compiled by The Associated Press, USA Today and Northeastern University that tracks every mass killing over the last 15 years shows that San Jose is the 15th mass killing so far in 2021, all of them shootings. Eighty-six people have died in the shootings, compared with 106 for all of 2020. The database defines mass killings as four or more people dead, not including the shooter, meaning the overall toll of gun violence is much higher when adding in smaller incidents."We do feel on edge, because a few years ago, we had the Gilroy shooting," said Amar Singh, referring to the shooting at the Gilroy Garlic Festival in 2019 that killed three people. "I have family, friends in the VTA. There's a large Sikh presence in the VTA. When I heard about this, my initial thought was FedEx mass shooting. Are we targeted?"In April, a 19-year-old opened fire at an Indianapolis FedEx facility, killing eight people. While the motive for the shooting remains under investigation, four of the victims were part of the city's Sikh community. Ninety percent of the employees at the FedEx warehouse are also part of the Sikh community. "It just kinda got me to thinking about your co-workers and you don't even know who you are working with anymore. You don't know who is capable of doing what," said San Jose resident Richard Yardley.— The Associated Press contributed reporting.