Todd Morgan, a spokesman at the Presley home in Graceland, said he had no information about the accident except that Dvorin was in a car with Ed Bonja, Elvis' official photographer and tour manager through most of the 1970s, including the photos for many of Elvis' albums.
No information has been released about whether Bonja was injured in the accident.
Dvorin had performed Saturday night at Trump 29 Casino in Coachella, California, with "American Trilogy," a concert by Elvis impersonator Paul Casey that included conversations with Dvorin and other Presley friends.
The phrase that Dvorin made his signature was first uttered by other announcers early in Presley's career. It was intended to disperse audiences who lingered at performance venues hoping for an Elvis encore.
"Al made it his own with his particular style," Morgan said. "He's the man when it comes to that saying."
Dvorin's version is captured on many official recordings of live performances, he said.
In an interview with The Desert Sun newspaper of Palm Springs, California, in advance of Saturday's show, Dvorin said he hadn't heard others use the phrase before he began saying it.
"Everybody and his brother has claimed the line and I'm sure Elvis's mother, when somebody called him, said, 'Elvis is not home. Elvis has left the building,"' Dvorin said. "As far as I know, I created it."
A former bandleader and talent agent in Chicago, Dvorin worked with Presley in the earliest days of his career as his stage manager and got him a gig as an opening act for country singer Hank Snow, a client of the then-unknown Colonel Tom Parker.
"I started working with Elvis before Parker signed him," Dvorin said.
Once Parker became Presley's manager, he hired Dvorin to book opening acts for the 1950s shows, according to the reference book "Elvis Day by Day." Parker preferred vaudeville-style openers, like jugglers and dancers, who wouldn't compete with Presley's star power and would help counter rock 'n' roll's juvenile delinquent image.
Dvorin said he began announcing Presley's shows after criticizing an announcer Parker had hired. Parker fired the man and ordered Dvorin to take on those duties.
"I had done every job except dye his (Elvis') hair and announce," he said.
Dvorin was with Presley on his last tour in 1977. The singer died of heart problems and drug abuse that August.
"To his dying day, he was modest. He was just a nice person," Dvorin said of Presley.
The announcer continued to appear at Presley commemorations in Memphis, Vegas and elsewhere, sharing his recollections of the King.
"He had a huge knowledge of show business spanning five decades," said Royal Talent, the agency that represented Dvorin, in a tribute on its web site. "He will be missed by all that knew him. Al has left the building, but will not be forgotten."
Dvorin is quoted and pictured on numerous Elvis fan web sites around the world.
"He's a fixture in (the) Elvis world. He'll be greatly missed," said Morgan, at Graceland.