Five people including a 4-month-old baby aboard a 40-foot yacht off the coast of Marina Del Rey were able to escape when the vessel caught fire Saturday afternoon, Los Angeles County Fire said.

"Within a minute, the boat was fully engulfed and we realized this was going to be quite a boat fire," said Jon Van Duinwyk, LA County Lifeguard.

Lifeguards were able to get out to the yacht quickly to help those aboard.

They said the passengers on the yacht were still on the bow as the lifeguards approached.

The vessel was approximately 200 yards off of the coast, LA County Fire said.

"We were screaming at them to jump off, and then we realized one of the women was holding a baby," Van Duinwyk said.

The fire moved so fast, authorities said the family didn't know what to do.

"They were petrified," Van Duinwyk said. "They didn't even have life jackets because the fire moved so fast."

As the occupants began jumping off, the mother and child fell five or six feet off the bow, plunging underwater, Van Duinwyk said.

Van Duinwyk grabbed the baby right away and let the family know he was a lifeguard.

Once he swam "as fast as he could" to the lifeguard's boat and handed off the child, he went back to help the rest of the passengers in the water.

"[I was] holding the baby over my head, swam her back to our rescue boat," Van Duinwyk said.

No one was injured on the yacht, but paramedics were checking the occupants for smoke inhalation.

The fire was knocked down by 4:15 p.m. on the yacht. It was unknown what caused the blaze to ignite around 3:25 p.m.

"The baby seems fine," Van Duinwyk said.

Van Duinwyk was reunited with baby Isabella and her grateful family later Saturday, captured on camera by NBC4.

"I feel relieved everyone is safe and sound," Gwidael Buchon, the yacht owner, said.

"Words don't express, we are happy," Theresa Gandler, the baby's mother, said. "Those are our two heroes, and I was very glad to see them."

Authorities suggested in this type of situation to always be aware of where the fire extinguisher is located on one's boat, to put on life jackets quickly, and swim away from the boat if the fire gets out of control.