Eyewitness News spoke to someone who knew all three deputies well for many years.
The deputies killed were identified as Deputy Joshua Kelley-Eklund, Deputy Victor Lemus, and Deputy William Osborn, who were all assigned to the Special Enforcement Bureau's Arson Explosives Detail. Between the three of them, the deceased employees had served in the department for 74 years.
Dep. Jason Zabala with LASD said the deadly incident is a reminder of just how dangerous their job is.
"I knew all three individuals... the best of the best," Zabala said.
Zabala says he worked closely with two of the deputies who were killed for the better part of 20 years.
"It's something you realize from day one that when you sign up for the job, you know it's going to be a dangerous job. As the years go on, you realize how dangerous it is. It's something that's always in the back of your mind, but you do this job for a reason. You don't really think about it day-to-day, until something like this happens, and then you realize just how dangerous it really is," Zabala said. "I know our families go through that, I know my family goes through that, probably every day. But, like I said, we truly like, love the work we do. We don't think about it every day, we just come to work, do our job, like I said, when something like this happens, it's just a tragedy."
While the investigation continues into what happened, the public is being asked by L.A. County supervisors, the deputy's union, and the department to support the LASD while they deal with the tragedy.
"So just understand, please, what our deputies are going through. To those who have reached out and offered their support and condolences, my heartfelt thanks to you, because we need it right now more than we've ever needed it," said Richard Pippin with the Association for L.A. Deputy Sheriffs.
"I'm sure they woke up this morning doing their job, and nobody thought that they wouldn't be able to go home today to their families," said L.A. County Supervisor Hilda Solis. "So yeah, we have to remember that, and praise them, and provide condolences, and unify around them -- especially the community here that worked with them for so many years."
"I can think of no greater honor, truly, than to die in the service of the people of L.A. County," Zabala said. "It's why we sign up. It's tragic, but I'm sure their families are proud of their service. As I am."
L.A. County Sheriff Robert Luna said it's the deadliest day in the department in over 150 years.
The investigation into the deadly incident is ongoing. Multiple law enforcement sources briefed on the investigation told ABC News that it appears the explosive that detonated had been brought back to the facility from a seemingly routine bomb squad callout and was believed to have been inert when it exploded.
East L.A. resident recalls hearing blast that killed 3 deputies
The community gathered on Friday evening as the deputies' bodies were processed from the scene to the medical examiner's office.
Eyewitness News spoke to a mother who brought her children out to pay their respects during the procession. The family brought an American flag to hold as the procession went by.
"We are three generations of immigrants here, and our community in East L.A., we're always downfall. Beautiful people and heroes come out of East L.A.," Analia Saavedra said. "And I wanted to show my kids that we do really care. And our condolences to the family, and I wanted them to see and show their expression of how devoted we are to our community."
The family lives just down the street from the training facility in a nearby residential neighborhood.
"We have history here, and I want my kids to be proud of where they are. We are a military family. We're proud citizens. My mom is 92, clean record, so good people come out of East L.A.," Saavedra said. "And we want to be thankful to those families and those deputies that really put their lives every day, and they don't even know if they are going to come home."
Saavedra said her family heard the explosion as they were getting ready on Friday morning.
"I was getting my little girl ready to go to summer school. At 7:20, we heard a boom. I was opening my gate. I was at a stoplight on Eastern and Floral when I see deputies come. I pulled aside, and I didn't even know where they were going," Saavedra said. "And her and I said, 'Man, bless them.'" When we got home, there were three lives that we had literally passed at 7:33 and they were laying there. It's hard. It's hard for them to know that."
Saavedra said it's important for her children to understand the sacrifices law enforcement officers make for their communities.
"They were human. They had lives. They had kids. They had children. We were just talking about it, and she said, 'Mom, I hope they didn't leave their house being mad at anybody.' And I said, 'You know what, we're going to pray.' And so I'm thankful, thankful," Saavedra said.