Fred Johnson, a local minister and member of the Fort Lauderdale Gay Men's Chorus, a tight-knit ensemble of about 25 mostly older men, was at the wheel of a pickup truck when his group was signalled as next to join the parade.

He suddenly accelerated forward, killing James Fahy, 75, and injuring Jerry Vroegh, 57, who was released from the hospital on Monday.

A third man, Gary Keating, was treated at the scene for minor injuries, according to a statement from Fort Lauderdale police.

Fahy and Vroegh planned to carry a banner in front of the chorus truck while other members walked behind to hand out leaflets.

"I love my Chorus family and the community and would never do anything to intentionally harm anyone," Johnson said in a statement.

"Please know that I hold my fellow chorus member, Jim Fahy, in my heart forever."

Fort Lauderdale police said on Monday that all evidence indicates the collision was a terrible accident, noting Johnson had fully co-operated with the investigation and there was no evidence that drugs or alcohol were involved.

Chorus members said Johnson was always helping others and carried snack bags in his car to hand out to the homeless.

"I talked to him yesterday and today," chorus member Bradley Bush told The Associated Press in a phone interview Monday.

"He's just really, really beside himself ... It's going to be a burden that he's going to carry the rest of his life."

In the initial aftermath of the accident, parade participants and witnesses did not know what to think.

A visibly shaken Fort Lauderdale Mayor Dean Trantalis initially declared it a terrorist act on the gay community.

On Sunday, he clarified it was an accident and said he misspoke the day before because he had been traumatised by what he witnessed.

June is Pride Month in the US, commemorating a June 1969 uprising that followed a police raid targeting gay patrons at the Stonewall Inn in New York.

It was a catalyst for the country's gay rights movement.

Australian Associated Press