(CNN) A chartered plane crashed into an Australian mall, killing all five people on board -- including four notable Texans on "trip of a lifetime."

A co-founder of a law firm. A retired CEO. A former FBI agent. A retired Dallas executive.

The men were killed shortly after the plane took off Tuesday from Melbourne's Essendon Airport. Authorities have not identified the Australian pilot, who also died.

While investigators try to determine what went wrong, new details are emerging about the victims.

Retired CEO was nervous about flying

Glenn Garland was one of four Americans killed.

Glenn Garland was having a great time golfing with friends on his trip to New Zealand and Australia -- and his Facebook account showed it.

"Melbourne is one magnificent and amazing city," Garland posted Monday, one day before the crash.

He shared his anxiety about flying in a small plane. Earlier in the trip, he said he was nervous about flying to Milford Sound in New Zealand.

"I only burned 5,000 calories of anxiety on the flight over," Garland posted on February 8. "Beats a 5-hour one way bus ride."

Garland was the CEO of Texas-based CLEAResult , an energy efficiency company, until his retirement in 2015. On Tuesday, the company said Garland was one of the passengers killed.

"We at CLEAResult are heartbroken to hear of Glenn Garland's passing," the company said in a statement. "Glenn was an inspirational leader who co-founded our company with a unique vision for the vast potential of the energy efficiency industry. Our deepest sympathies and thoughts are with his family during this difficult time."

Former FBI agent took 2nd chance at love

Greg Reynolds De Haven was in Australia with his wife, Rosemary.

Another Texan, 70-year-old Greg Reynolds De Haven, was on the golfing trip to Australia, his sister Denelle Wicht told CNN. The retired FBI agent had served 30 years with the agency and was enjoying a vacation with his wife and friends.

"Golf was always his first love," Wicht said. But she said his second wife, Rosemary, was the love of his life.

"He met this wonderful woman and took a chance again," Wicht said. "She had given him the best years of his life. She was the best thing that could have ever happened to him."

De Haven's wife was shopping with friends in Melbourne and was not on the plane, Wicht said.

De Haven also is survived by two sons, a daughter and six grandchildren.

Co-founder of law firm had just started retirement

Texas lawyer Russell Munsch had just retired after a nearly 40-year career.

Russell Munsch was a third Texan killed in the crash. He co-founded the law firm Munsch Hardt and had recently retired after a nearly 40-year career.

"It is with great sadness that we inform you our dear friend, colleague, and co-founder Russ Munsch passed away in a tragic plane crash in Melbourne, Australia," the law firm said in a statement.

"Russ was enjoying retirement, and doing what he loved almost more than practicing law -- playing golf. Russ was a lawyer's lawyer, one of the best of all time. ... Russ was a loving husband, father and friend, and he will be dearly missed."

Beloved father who loved golf

Retired Texan executive John Washburn (C) with his family.

John Washburn, a 67-year-old retired lawyer, was the fourth US citizen on the plane.

His family said he was looking forward to playing golf with his close friends Glenn, Greg and Russell.

"Our dad was an exceptional father and husbands, who was kind and generous and always put his family first," family members said in a statement.

"Everyone who met him noted how happy and smart he was. He adored his wife and always supported his children."

His family said their father lived in Spicewood, Texas, after retiring several years ago as an executive and general counsel at Sammons Enterprises in Dallas.

"The four men on the plane were good friends, and they and their wives were going on what they themselves called a 'trip of a lifetime,'" the statement said.

'Very lucky' no one was in mall

JUST WATCHED Footage shows plane crash aftermath Replay More Videos ... MUST WATCH Footage shows plane crash aftermath 00:45

No one was inside the still-closed DFO Essendon shopping center when the plane went down about 9 a.m., officials said, but some nearby witnesses were being treated for shock.

"It was a catastrophic plane crash that has taken a number of lives," Victoria police Assistant Commissioner Stephen Leane said. "But certainly if we look at the circumstances, we've been very lucky today depending on the time of day and who was around."

The mall will remain closed for another day, police said Tuesday.

Cause of crash uncertain

Lisa Neville, Victoria's minister for police, told reporters that the cause of the crash is "still being confirmed by police and fire services," CNN affiliate Seven Network reported.

The plane crash is visible Tuesday from the tarmac at Melbourne's Essendon Airport.

Neville said she believed the plane was a Hawker Beechcraft.

All flights in and out of Essendon, a smaller airport that is separate from Melbourne Airport, were temporarily suspended. Some parts of the usually packed Tullamarine Freeway were closed for part of Tuesday due to scattered debris from the crash.

The DFO Essendon shopping center has been damaged after the plane crashed into it.

Aerial pictures from Seven Network showed damage to the roof and infrastructure of the shopping center.

Prime Minister Malcolm Turnbull tweeted he was "deeply saddened" by the crash.

"Our hearts and prayers are with the victims and their families," he said.