The New York Post reported that police sources said the shooter hit Cali with multiple bullets and a 911 caller said they heard six or seven shots.
There was also a report of a blue pickup truck leaving the scene around that time.
As he strolled out of his red-brick mansion on Staten Island the reputed mob boss Francesco "Franky Boy" Cali probably felt safe.
The mobster emerged from his home around 9:15 p.m. after the gunman backed his pickup into Cali's Cadillac SUV, damaging it, according to police.
Cali is the first mob boss to be murdered in NY since Gotti ordered the infamous hit on Gambino boss Paul Castellano, having him gunned down in front of Sparks Steak House in Manhattan in December 1985.
Castellano's death led to the rise of John "Dapper Don" Gotti, who then took over as Gambino family boss, running criminal enterprises ranging from gambling to money laundering to prostitution.
Cali's only criminal conviction came from an extortion charge in 2008 for trying to shake down a trucker; he spent 16 months in prison. He was sentenced to life in prison and died of cancer in 2002.
The post-Gotti chapter saw the mob's influence on the U.S. eastern seaboard wane - but Wednesday's hit threw NY back to its golden years of organized crime.
While it has been decades since a mafia boss was killed in NY, lower-level members have been attacked or killed in recent years.
Federal prosecutors referred to Cali in court filings in recent years as the underboss of the Mafia's Gambino family, once one of the most powerful and feared crime organisations in the country.
"We thought those days were over", Mayor Bill de Blasio said of Cali's slaying.
Gambino headed the organization until 1976, when he handed power over to his brother-in-law Paul Castellano.
He was assassinated outside Sparks Steakhouse in Manhattan in 1985.
Last October, Bonanno crime family associate Sylvester Zottola, 71, was gunned down at a Bronx McDonald's drive-thru as he waited for a coffee.
A witness said that his family members rushed outside after Cali was gunned down.
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Options include a long delay, exiting with Mrs May's deal, leaving without a deal or even another referendum . Selmayr also raised his doubts that May would be precise in her request, adding "she never has been before".