Photo: The Canadian Press

A pilot repeatedly yelled out "Mayday" but did not say what the emergency was before his light plane crashed into the roof of an Australian shopping mall, killing himself and four American tourists, an accident investigator said Wednesday.

Police blamed "catastrophic engine failure" when a twin-engine Beechcraft B200 Super King Air crashed into the Direct Factory Outlet mall in the Melbourne suburb of Essendon on Tuesday moments after takeoff from a nearby runway.

But Australian Transport Safety Bureau chief commissioner Greg Hood said modern twin-engine aircraft are designed to continue flying if an engine failed.

"My understanding is he only used the word 'Mayday' a number of times," Hood told reporters, referring to radio communication from pilot Max Quartermain to air traffic controllers.

"My understanding is he didn't refer to the specific nature of the emergency," Hood said.

Quartermain was the 63-year-old owner of the charter company Corporate and Leisure Travel.

The passengers were identified as Greg Reynolds De Haven, Russell Munsch, Glenn Garland and John Howard Washburn, who all lived in the Austin, Texas, area.

Quartermain was investigated by the Australian Transport Safety Bureau after a near mid-air collision that happened in September 2015.

Because of that incident, the Civil Aviation Safety Authority, the industry regulatory, required Quartermain to undergo proficiency tests to demonstrate he could fly a plane by instruments alone, authority spokesman Peter Gibson said. Quartermain passed those tests weeks after the near-miss, Gibson said.

Hood said he would not comment on Quartermain or his flying record. He added his flying record as well as the plane's maintenance record would be part of the crash investigation. Australian Transport Safety Bureau investigators are to compile a preliminary report within 28 days.

The bodies were removed from the wreckage on Tuesday, said Police Superintend Mick Frewen.

The busy shopping mall had yet to open for the day when the plane crashed after taking off from Melbourne's second-biggest airport at Essendon for a golfing trip to King Island.