Details of his death were unclear. Councilmember Monica Rodriguez announced Alatorre's death during Tuesday's council meeting.
Alatorre, who was born in Texas but raised in East Los Angeles, worked as an aide to Assemblyman Walter Karabian before winning election himself in 1972. He served in the Assembly until 1985, when he won a special election to represent the Los Angeles City Council's 14th District.
His victory in that race was seen as a major boon to Los Angeles' Latino community, since the council had not had a Latino member since the 1962 departure of Edward Roybal.
Alatorre remained on the council until 1999, including stints as chairman of the council's Public Safety and Budget and Finance committees. He also served on the Los Angeles Regional Transportation Commission, which later evolved into the current county Metropolitan Transportation Authority, or Metro. He was the first MTA chairman, leading the charge for the creation of the Metro Gold Line and its extension into East Los Angeles.
"Councilman Alatorre was an icon in Los Angeles who blazed the trail for generations of Latino leaders in Los Angeles and California," Mayor Karen Bass said in a statement. "His fervent advocacy served as a beacon of hope for millions and his dedicated advocacy has resulted in a legacy that will benefit millions more in the years to come. I had the honor of knowing the Councilman and the great benefit of receiving his counsel and guidance based on his prolific experience. My thoughts are with his family on this sad day and with the so many Angelenos whose lives were made better from his service."
Alatorre is survived by his daughter and two sons.
City News Service contributed to this report.