Four American golfing buddies and their Australian pilot were killed Tuesday when their small aircraft crashed moments after take-off in Melbourne – exploding in a giant fireball likened to “an atomic bomb.”

The twin-engine Beechcraft King Air had just taken off from Essendon Fields airport when the pilot reported a “catastrophic engine failure” and tried to return to the airport.

The plane veered into a mall and crashed into a storage area in sight of horrified rush-hour motorists about 9 a.m. local time, officials said.

“Looking at the fireball, it is incredibly lucky that no one was at the back of those stores or in the car park of the stores, that no one was even hurt,” Victoria Police Assistant Commissioner Leane said.

The Americans were identified as Texans Greg Reynolds De Haven, Russell Munsch, Glenn Garland and John Washburn, Melbourne’s Herald sun reported.

De Haven’s sister Denelle Wicht notified her Facebook followers about the death of the 70-year-old retired FBI agent who had served in the US Army during the Vietnam War.

“Dear friends and family, my handsome athletic big brother was killed today in a plane accident while on his ‘once in a lifetime’ trip to Australia,” she wrote.

Munsch, a lawyer, was the founding partner of the Munsch Hardt Kopf & Harr firm in Austin, according to his LinkedIn page.

He had litigated some of the most prominent bankruptcy cases in the US, including the 2001 case of Houston-based Enron Corp., one of the largest energy companies in the world before its collapse.

Garland retired in 2015 as the CEO of green energy firm CLEAResult Consulting Inc. in Austin, according to the Austin Business Journal.

A day before the tragedy, he wrote on Facebook about his golfing trip.

“We had rain squalls, and wind that was almost biblical in the fierceness. The only thing we missed was a plague of locusts. My hat is off to the Aussies that play in this everyday,” he wrote.

The co-founder of CLEAResult described Garland as a “visionary.”

“I am devastated to hear of his passing and my heart and thoughts are with his family. We have all lost an incredible man,” Jim Stimmel told The Post in a statement.

Washburn, 67, was a former general counsel at Sammans Enterprises in Dallas, the Austin American-Statesman reported.

The veteran pilot, Max Quartermain, 60, who owned the charter company Corporate and Leisure Aviation, had been under investigation in connection with a “near collision” in 2015, news.com.au reported.

In an incident report, the pilot of the other plane described Quartermain’s actions as “unsafe.”

The probe had been deferred three times because of “workload,” according to the Australian Transport Safety Bureau.

Friends and fellow aviators described Quartermain as a “fine pilot” and “champion bloke.”

“We feel the loss of part of the family very deeply. Max was one of the Essendon family, and we’re sad and we miss him,” Mike Falls, head of Shortstop Jet Charter, told news.com.au.

The ill-fated plane took off for a golfing trip to King Island in Tasmania, about 160 miles to the south, officials said.

A witness who gave his name as Jason told Australian Broadcasting Corp. that he was passing the mall in a taxi when the plane crashed.

“I saw this plane coming in really low and fast. I couldn’t see the impact but when it hit, the building there was a massive fireball,” he said about the worst aviation accident in Australia in 30 years.

“I could feel the heat through the window of the taxi, and then a wheel — it looked like a plane wheel — bounced on the road and hit the front of the taxi as we were driving along,” he said.

With Post Wires