"Though authorities are still gathering information, we know two individuals marching to celebrate inclusion and equality were struck by a vehicle", Broward County Sheriff Gregory Tony said in a statement.
A man rammed a truck into a group of marchers at a Stonewall pride parade in Wilton Manors, Florida, on Saturday.
Adamson said police are speaking with the driver and witnesses.
Trantalis said he believes the crash was "deliberate" and an attack against the LGBTQ community.
Detective Adamson said authorities were investigating "all possibilities" with the help of the Federal Bureau of Investigation, but did not say whether they believed the incident was intentional.More news: Edwin Poots: Fallout from DUP leader's resignation continues
While the truck appeared to be taking part in the procession, it was not immediately clear if the crash was a deliberate assault or an accident.
"We are devastated having witnessed this horrific incident".
Lauderdale Mayor Dean Trantalis is facing backlash for calling a deadly crash at a Pride parade in the Florida city a "terrorist attack against the LGBT community" before all the facts emerged.
"It was definitely an intentional act right across the lanes of traffic".
The Wilton Manors Mayor Scott Newton responded to the incident, saying in a statement, "A tragic incident occurred at today's Stonewall event". My staff, volunteers and I are thankfully safe'. "I'm proud of all the BSO and local first responders who leaped into action, running into the unknown and instantly provided care for the victims".More news: B.C. records four COVID-related deaths, 113 new cases
"We're praying for the victims and their loved ones as law enforcement investigates, and I am providing them with whatever assistance I can", Wasserman Schultz added.
She added: "I am so heartbroken by what took place at this celebration".
Justin Knight, the president of the Fort Lauderdale Gay Men's Chorus, said through a spokesman to WPLG that the driver and the victims were all members of the community. "We ask for patience as we work to conduct a thorough and complete investigation".
In a statement, Wasserman Schultz said she was safe but "deeply shaken and devastated that a life was lost". May the memory of the life lost be for a blessing'.
The parade has been put on hold and police are on the scene, NBC affiliate WTVJ reports.More news: Senate OKs Legislation To Make Juneteenth A Legal Holiday
June is Pride Month, which commemorates the 1969 Stonewall riots sparked by repeated police raids on a popular gay bar in NY.