One person was killed and 10 were injured in a hit-and-run boat crash off the coast of western Florida.

A ferry carrying 45 people over calm water was unexpectedly struck from behind by a 36-foot recreational boat at high speed late Sunday night.

The pilot of the boat fled the scene and was later caught, although he isn't facing charges at this time. The crash was declared a mass casualty event by emergency services.

“Even before the first responders arrived on scene, we knew we were dealing with a major situation,” Clearwater Chief of Police Eric Gandy told reporters Monday, describing “horrific screaming" in the background of 911 calls.

Mass casualty event

The tragic accident happened late Sunday night near the Memorial Causeway Bridge, which links the city of Clearwater with Clearwater Beach.

A ferry was carrying 45 people on the last day of a sand-sculpting festival, the Sugar San Festival, when a boat slammed into the ferry from behind at high speed. The impact crumpled the ferry's stern and tore open the canopy. The ferry came to rest on a sandbar.

First responders encountered a chaotic scene.

"When our crews first arrived, they found themselves in the water trying to rescue people,” Tony Tedesco, EMS chief for Clearwater Fire Rescue, said. “On top of that, they’re trying to figure out who was the most injured.”

The injured passengers were triaged at a boat ramp and sent to different hospitals. Two people had to be airlifted for treatment, and one was pronounced dead.

Pilot wasn't drunk

The man piloting the recreational boat, Jeff Knight, was not drunk, authorities said. He complied with and passed a breathalyzer test.

Knight initially fled the deadly accident, which killed a 41-year-old passenger on the ferry, Jose Castro, of Palm Harbor. Knight was found 3.5 miles away from the scene on his boat.

According to police, Knight rode over three-quarters of the ferry with his boat. A 31-week pregnant mother was thrown from her seat during the harrowing experience.

“It’s very scary. I fell between two seats, and my whole body hurts right now,” the woman, Brenda Alvarez, told ABC Action News.

“We can’t understand how fast they were going, like how that was even logically possible that they hit and were able to get off like that,” she added. “It shattered the whole back of the boat, left a huge dent.”