The demonstration was one of many that were being held nationwide as part of what National Nurses United, the largest organization of registered nurses in the U.S., described as a "week of action."
"Say his name! Alex Pretti!" the marchers chanted. Some held signs that said "OUR PATIENTS' RIGHTS HAVE NO BORDERS."
The rally was held outside the Ronald Reagan UCLA Medical Center.
After the death of Pretti, a registered nurse, the demonstrators called for Senate and House to vote down any spending package that includes funding for Immigration and Customs Enforcement.
"It is a core value to advocate for our patients and our communities," Roxette Villegas, an ICU nurse, told ABC7. "What Alex Pretti was going -- he was doing the exact same thing. He was using his nursing experience to advocate outside of the hospital."
Two federal officers involved in the shooting of Pretti have been placed on paid administrative leave, according to multiple sources familiar with the situation.
The sources told ABC News on Wednesday that this is standard operating procedure when there is an officer-involved shooting.
2 federal officers involved in shooting have been placed on administrative leave
One federal officer involved is a Border Patrol agent and the other is a Customs and Border Protection officer, according to a Department of Homeland Security notification to Congress, obtained by ABC News on Tuesday. Both discharged their weapons, according to the notification.
ABC News contributed to this report.