The local vendors were crossing Riverside Drive around 11:15 a.m. when the suspect's vehicle collided with them and their fruit cart, Ontario police said in a statement.
One of the vendors, later identified as Ariel Tucubal Rabinal, was pronounced dead at the scene, while the second vendor was transported to a local hospital in critical condition.
An eyewitness to the crash described the violent collision.
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"Turned to go around him and that guy never even seen her. And it took him straight out -- I mean killed him," Walter DeCroix told Eyewitness News.
The driver -- identified as 43-year-old Jessica Dewet of Chino -- was transported to a local hospital with minor injuries. Dewet is suspected of driving under the influence of alcohol/drugs and was arrested on charges of felony driving under the influence and gross vehicular manslaughter, police said.
A GoFundMe account set up on behalf of the vendor who was injured, Héctor Rabinal, surpassed $4,000 as of Tuesday morning.
Rabinal's brother, Carlos, said he has worked nearly every day to send money back to their family.
He spoke to Eyewitness News in Spanish, saying his brother is a hard worker and has two children in Guatemala. Carlos said Héctor came to the U.S. to help their family have a better future.
One woman who shopped at Rabinal's fruit cart said she was shocked to learn of the incident.
"My first thought was, no it can't be that guy -- I just saw him yesterday, too," said Ontario resident Rosio Rodriguez.
Another man who lives in the area said he frequently sees cars speed on Euclid Ave.
"Speed limit is 50 miles an hour, and I'm sure some people go 55 to 60. It's like a freeway, but it's actually just a street here," said the man, who identified himself as Eddie.
A makeshift memorial near the site of the crash continues to grow, with mourners leaving flowers and candles.
CORRECTION: A previous version of this story identified the deceased victim as Héctor Rabinal.