The incident happened around 6.45pm ET on Saturday when a family, including three children, were on their way to a 15th birthday party at a home across the railroad crossing.
The Hillsborough County Sheriff’s Office said that seven people were in the white 2020 Cadillac Escalade – including a husband and wife, two children, an adult child and two friends of the children.
All seven are believed to be residents of Plant City, Florida.
Police said that the vehicle was driven onto the tracks in the path of an oncoming train.
At a press conference, Hillsborough County Sheriff Chad Chronister said that “the conductor of the train did everything he could to slow this train down, he signalled these loud train horns that they are all equipped with along with the flashing lights”.
The SUV was struck by the train going at around 55mph, causing it to “catapult and flip violently several times before it landed a distance from this crossing”.
Five of the rear-seat passengers were “violently ejected from the SUV”.
After the car landed, the sheriff said it looked “like a soft drink can that has been smashed”.
It is still “unknown and undetermined” why the driver slowly crossed the tracks directly in the train’s path, police said in a statement.
A witness who was parked by the tracks was hitting his horn, trying to get the driver’s attention as the train approached, the sheriff said.
Five victims – identified by police as Julian Hernandez, 9, Jakub Lopez, 17, Alyssa Hernandez, 17, Anaelia Hernandez, 22, and Enedelia Hernandez, 50 – were found dead after being thrown from the car in the crash.
First responders used jaws of life to get the front-seat passenger and the driver out of the car.
The driver, Jose Hernandez, 52, was taken to hospital but died overnight.
Now, the front-seat passenger, identified by his family as Gullermo Gamma III, is currently the only family member who has survived the incident. He remains in critical condition at Lakeland Regional Hospital.
“Our hearts are shattered for the loss of this family and the tragedy that occurred here this evening,” said the sheriff.
“We are all rattled to our core.”
Mr Gamma’s aunt, Jennifer Cantu, has launched a GoFundMe campaign to raise funds for her nephew’s recovery.
On the donation page, she said he was the boyfriend of one of the victims killed in the crash.
“My family and I are living through one of the most tragic episodes of our lives,” she wrote.
The railroad crossing is not equipped with gates or signals, as it is a private road for a few houses rather than a regularly travelled public track. It only has a railroad crossing and stop signs.
CSX confirmed that one of its trains was involved in the crash.
“There were no injuries to the crew of the train. CSX extends its deepest sympathies to everyone impacted by this tragic incident,” the company said in a statement to WFTS.
“CSX is working to support local law enforcement as they conduct the ongoing investigation.”