Irish tourist Ian McTiernan, from Northern Ireland but living in Boston, had just left the beach in Stuart, Florida when a man kite surfing was killed by sharks.
Stephen Howard Schafer, 38, was kite surfing on Stuart beach just before the shark attacked and killed him.
"It was the most frightening thing I've ever heard," said McTiernan, who was vacationing with his girlfriend in Palm Beach, Florida and had taken a drive to Stuart Beach, Florida just hours before the attack.
McTiernan said he had spent the morning swimming with his girlfriend and "luckily" left the beach a few hours before the attack.
"Imagine that could have been us," said McTiernan.
A spokeswoman from Martin County Sheriff’s Office, Rhonda Irons, said that a lifeguard spotted the man floating about a quarter-mile offshore in an unguarded stretch of ocean.
The lifeguard raced towards the water on a rescue board and pulled Schafer away from the sharks.
Schafer was taken to Martin Memorial Hospital, where he died.
Although McTiernan will continue his vacation in Florida, he swears he will stay out of the water there.
"I'm not taking any chances," he said.
"I've been here 25 years," McKinley said. "To my knowledge, this is the first shark-related fatality we've seen."
However, several beaches have been closed in Florida in recent days as thousands of migrating sharks have been spotted off the coastline.