KEY BISCAYNE, Fla. -

Lazaro Mendez, better known as DJ Laz, was steering the vessel that killed a 23-year-old man after a day of partying on the Key Biscayne sand bar Sunday night, authorities said.

On social media, Mendez and his friend recording artist Pitbull had been promoting Voli Vodka, the brand that was hosting the Sunday party that had a tragic end in Nixon Cove, near Bill Baggs Florida State Park.

"I am incredibly distraught over the unfortunate accident," Mendez said Monday on Facebook. 

About 7 p.m., a console fishing boat got stuck on a sandbar. No one wanted to wait until high tide at 1:30 a.m., so a group moved to push the boat. Mendez was steering the boat, authorities said.

Ernesto Hernandez, 23,  was on a nearby boat and jumped out to help. He ended up on the back of the vessel. Witnesses watched in horror as his torso got caught on the boat's moving propeller, Florida Fish and Wildlife Conservation Commission spokesman Jorge Pino said.

On Facebook, Hernandez posted he was a Southwest Miami Senior High 2008 grad, had attended Miami-Dade College and worked at Executive Protection. He also worked as a driver at South Beach exotic rentals.

Hernandez was airlifted to Jackson Memorial Hospital, where he was pronounced dead.

"My family and I send our heartfelt condolences to the family and friends of Ernesto Hernandez," Mendez said on Facebook. "They are in our thoughts and prayers."

It was a horrific ending to the Cinco de Mayo celebration Sunday.

"There were like 20 boats tied up next to each other. They were throwing out bottles of Corona," Annabelle Lebaz, of Flyboard 305, said."People were getting really drunk for most of the day."

In Florida, boaters are allowed to drink, except for the person steering the vessel. Pino said Mendez did not show any signs of impairment, but could face criminal reckless or negligence charges.