When federal agents arrived at two Los Angeles elementary schools last week to conduct welfare checks on students who the agents said were undocumented, fear and outrage spread among parents, teachers and administrators.

For the superintendent of the Los Angeles Unified School District, the visit by federal agents was something more. It was personal.

Alberto Carvalho, the leader of the second-largest public school system in the country, was once undocumented, too.

“Their journey is no different than my own,” Mr. Carvalho said in an interview, referring to the estimated one in four students who are undocumented in his district. “Maybe the country of origin is different, but in many, many instances, the journey is exactly the same.”

At a news conference after the visit, he condemned the agents’ actions. His speech drew national attention on social media, and his acknowledgment of his own former status as undocumented represented a rare moment in an era of immigration crackdowns.

Mr. Carvalho told those gathered outside the Los Angeles Area Chamber of Commerce that if it sounded like he was coming across with “a certain degree of contempt and anger,” that was because he was.