The filmmaker – who previously contributed to the New York Times – was gunned down by Vladimir Putin’s troops while travelling in a car in Irpin, just outside Kyiv.
Another reporter, said to be Mr Renaud’s colleague, is being treated at a hospital in the Ukrainian capital after being injured in the attack.
Juan Arredondo, who was wounded in the lower back, told Italian journalist Annalisa Camilli he and Mr Renaud were shot after they were stopped at a checkpoint just after a bridge in Irpin.
“We crossed the first bridge in Irpin. We were going to film other refugees leaving and we got into a car, someone offered to take us to the other bridge,” he said.
“We crossed the checkpoint and they started shooting at us. So the driver turned around and they kept shooting.”
Mr Arredondo said his colleague, who he named as Mr Renaud, was hit in the neck and remained on the ground earlier on Sunday.
Andrey Nebitov, the head of the Kyiv region police, said the 50-year-old filmmaker “paid his life” for reporting on the invasion.
“A world-renowned media correspondent was shot in Irpin today,” Nebitov said.
“Another journalist is injured. Now they are trying to remove the victim from the war zone.
“Of course, the profession of a journalist is a risk, but US citizen Brent Renaud paid his life for trying to highlight the aggressor’s ingenuity, cruelty and ruthlessness.”
Initial reports suggest Mr Renaud worked for the New York Times, but Cliff Levy, the newspaper’s deputy managing editor, said he was not on assignment for the publication.
“We are deeply saddened to hear of Brent Renaud’s death. Brent was a talented photographer and filmmaker who had contributed to the New York Times over the years,” Mr Levy said in a statement shared on Twitter.
“Though he had contributed to The Times in the past (mostly recently in 2015), he was not on assignment for any desk at The Times in Ukraine.
“Early reports that he worked for The Times circulated because he was wearing a Times press badge that been issued for an assignment many years ago.”
It comes as terrified locals continue to flee to Kyiv from fierce battles and shelling in surrounding areas like Hostomel and Bucha.
In Irpin, a suburb about 12 miles northwest of central Kyiv, bodies lay out in the open Saturday on streets and in a park as shelling continues to rain down.
It comes as the battle around the capital rages on as Russian forces close in, with brave Ukrainian soldiers setting up tank traps on the streets to repel invaders.
Putin’s troops are inching closer and are believed to be just 15 miles from the city.
But Volodymyr Zelensky warned the Russians would only be able to take control of Kyiv if they “raze it to the ground” as the Ukrainian president confirmed around 1,300 of his troops had been killed since the conflict began.
Ukraine remains defiant as officials say Kyiv is “ready to fight” as presidential adviser Mykhailo Podolyak branded it a “city undersiege” and confirmed checkpoints were prepared.
“Kyiv will stand until the end,” he added.
Meanwhile, a Ukrainian MP has said the fight for Kyiv will be Russia’s new “Stalingrad if they want to make it so”
Speaking on BBC’s Radio 4 Today programme, Sviatoslav Yurah said: “It’s a massive town of millions and if the Russians try to come in they will have quite a fight on their hands – this will be their Stalingrad if they want to make it so.
“Nobody is going to surrender – I can definitely guarantee you that.”
Meanwhile, at least 35 people have been killed in a Russian airstrike at a base where foreign instructors were helping Ukrainians just 12 miles from the Polish border.
Russian forces fired more than 30 cruise missiles at the Yavoriv military base near Lviv, injuring 134 people, according to Ukrainian authorities as Kyiv warns Putin could start “provoking” Nato countries.
Foreign military instructors have worked at the Yavoriv International Centre for Peacekeeping and Security – but a Nato official said there were no personnel from the alliance at the base at the time of the strike.
Regional governor Maksym Kozytskyy said Russian planes fired around 30 rockets at the facility – with some were intercepted before they hit.