The riot began after an off-duty police officer, Patrolman Anthony Cinquemani, while trying to break up a fight, shot and killed a Puerto Rican man named Renaldo Rodriquez who had a knife and lunged toward him.
The descendants of original migrants were influenced by several factors such as the Civil Rights Movement, the Vietnam War, the urbanized environment and industrial decline along with increased levels of racial and economic segregation.
Skepticism was encountered with the story and protests happened afterwards and the Upper West Side's New York City Police Department was picketed.
[7] The second major incident in the area involving Puerto Ricans being killed by the police that led to raised tensions occurred on February 17, 1964.
The picketing was sponsored by the East Harlem Tenants Council, a rent strike group that was created five days earlier.
[7] Just after midnight on July 23, 1967, two plainclothes off-duty police officers, Thomas Ryan and Anthony Cinquemani, were cruising the Spanish Harlem neighborhood.
[8] Mayor John Lindsay visited the area where the riots happened that day as he was legally mandated to by state law and attempted to cool down the violence by talking to the crowds that had gathered.
During the times he visited the area he urged the local Puerto Rican community to create committees where they would meet at the mayor's residence, Gracie Mansion, to hear their issues.
During the meetings later in the day, an agreement was reached that said local leaders would restore in the area if the Tactical Patrol Force was temporarily decommissioned.
[10] At 10 PM a group of teenagers constructed a barricade that consisted of overflowing trash cans on Third Avenue and 111th Street and lit it on fire.
[11] Violence began after a crowd of 1,000 "attacked" a Gulf Oil gas station on 109th Street which they incorrectly thought was a shelter for the police.
[14] They were incited by a man giving speeches in Spanish nearby on Third Avenue and 111th Street about Puerto Ricans serving in the Vietnam War.
At some point during the rioting that night, a group of youths drew a chalk line across Third Avenue at 110th Street in Manhattan and wrote that it was the "Puerto Rican border.
Mayor Lindsay expressed concern about the possibilities of civil disturbances spreading to other Puerto Rican neighborhoods in the city and neighboring Central Harlem.
Also during July 26 the city's Police Commissioner, Howard R. Leary, ordered the entire patrol force to be on a six-day work week and give a 60% increase towards the number of officers available for anti-riot activities in an attempt to prevent any unrest in East Harlem from happening.
[12] In addition to the unrest in Harlem and the Bronx, new violence hit other parts of the city as looting and vandalism erupted in Midtown during the night of July 26 and 27.
[16] At 11:30 PM on July 26, officers at a station on 51st Street reported that a crowd that was disorderly consisting of 100-150 youths leaving Central Park from a Rheingold Festival.
[18] Another riot happened in the neighborhood of Brownsville in Brooklyn after an African-American police officer had killed a 14-year-old African American who was attempting to mug a Jewish man.
A false rumor spread that it was a white police officer, which lead to inciting residents in the area with three consecutive nights of disturbances along Ralph Avenue from Bergen Street to Eastern Parkway.
[20] Also in 1968, two incidents of unrest not connected to the King assassination riot happened during July in Coney Island and the Lower East Side at close to the same time.
Some Puerto Ricans turned to the Young Lords as they felt more moderate forces like Mayor Lindsay could not solve their problems.