Six people are dead, including three children, after a train struck an SUV as it crossed railroad tracks in Hillsborough County, Florida, Saturday evening, according to the sheriff's office.

Responders had been left shaken by the resulting scene of carnage, which left the Cadillac Escalade SUV looking "like a soft drink can that's been smashed," Hillsborough County Sheriff Chad Chronister told a news conference Saturday.

The freight train had been traveling at over 55 mph when it hit the SUV, which was taking seven people to a quinceañera party, Chronister said.

Video footage taken from a camera on the front of the train appeared to show the SUV's driver pulling up to the crossing and driving slowly across, without stopping to look both ways, the sheriff said.

The conductor of the train did everything he could to slow down as the vehicle approached, as well as sounding long horns and flashing the train's lights in warning, he said. A witness parked by the tracks said he also hit his horn to alert the SUV driver, Chronister said.

After being struck, "the SUV, we can see from the video, begins to catapult and flip violently several times before it landed a distance from this crossing," Chronister told reporters.

Deputies and first responders arrived at the scene of the collision just before 7 p.m. Saturday and immediately began rescue efforts, Chronister said.

First responders were able to rescue the driver and front seat passenger of the SUV, and took them to the Lakeland Regional Hospital in "critical and serious condition," Chronister said.

The other five passengers of the smashed Escalade were all "violently ejected" and pronounced dead at the scene, Chronister said.

Sheriff's office spokesperson Jessica Lang told CNN Sunday that the driver of the SUV died overnight in the hospital.

Lang identified the deceased as Julian Hernandez, 9; Jakub A. Lopez, 17; Alyssa Hernandez, 17; Anaelia Hernandez, 22; Enedelia Hernandez, 51; and Jose G. Hernandez, aged 52.

The victims' connections to each other were still being established, Chronister said Saturday, but added, "I believe tonight Hillsborough County lost one of its families." He said scene of the crash had been horrible to see.

"Anyone who goes and sees the carnage that's been created, whenever you compound that with the fact that some children lost their life here, maybe an entire family lost their life here tonight -- we are all visibly shaken," Chronister said. "We are rattled at our core after witnessing what happened here tonight."

The railroad crossing where the collision occurred does not have level crossing arms to stop cars from crossing when a train is passing through, Chronister said.

He said it is marked with a stop sign and railroad crossing indicator to encourage people to stop and look both ways before crossing. There are only a few homes on the other side of the railroad crossing and it is not a very well-travelled area, the sheriff said.

The sheriff's office is investigating the cause of the crash.