Pilot of plane that crashed near Melbourne called 'mayday' several times, authorities say

— -- The pilot of a plane that crashed into an Australian shopping center called "mayday" several times before the crash on Tuesday, authorities said.

The pilot did not specify the nature of the emergency before the twin-engine Beechcraft crashed near Melbourne, killing four American tourists, the Australian Transport Safety Bureau said in a press conference Wednesday morning local time.

Portions of the aircraft are still on the roof of the shopping center and in the parking lot, ATSB officials said. Investigators have completed of sweet of the runway for plane parts. Officials are also interviewing people who were on the runway at the time of the ill-dated takeoff, including pilots who also fly the Beechcraft and may have some helpful observations as to what they dash.

The crash was also documented on dashcam video, which investigators are looking into for clues.

The sister of one of four Americans killed when remembered her brother as "handsome" and "athletic."

"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. It was a charter flight with 2 of his friends flying to another island to play golf," Denelle Wicht, the sister of Greg Reynolds De Haven, wrote on Facebook.

Wicht told ABC News that her brother was traveling in a group, and that the husbands had split up with their wives for the day. She said that the group had been traveling for two weeks before the accident took place.

"Greg was on a vacation trip with a group of friends and wives. They were to spend three weeks in Australia, and I think they were there for two weeks plus when this happened. The group was spending the day going separate ways, there are other wives who lost their husbands. So so sad. Such a great guy," Wicht said in a Facebook message.

The plane had taken off from Essendon Airport around 9 a.m. local time and suffered a "catastrophic engine failure" in the air, according to Victoria Police assistant commissioner Stephen Leane.

The pilot attempted to return to the airport and crashed into the DFO shopping center, Leane said. There were no fatalities on the ground, he added.

The pilot of the plane was Max Quartermain, who owned the charter company Corporate and Leisure Travel, according to The Associated Press.

A State Department official confirmed that four U.S. citizens were aboard the flight. “We extend our deepest condolences to the families and loved ones of all those who died in today’s tragic crash," the official said.

Victoria's premier, Daniel Andrews, called the incident the “worst civil aviation accident in our state” in 30 years.

The identities of those who died and the nationality of the fifth victim were not immediately known.

“We extend our deepest condolences to the families and loved ones of those who died in today’s tragic crash," a spokesman for the U.S. Embassy in Canberra said.

ABC News' Tom Liddy, Benjamin Gittleson, Kirit Radia, Joseph Simonetti, and Matthew Stone contributed to this report.