SYDNEY - The Australian skydiving company which oversaw a tragic jump in which a Singaporean, Mr Mario Low Ke Wei, and his instructor died has expressed sympathy for the families of the victims, saying that "sometimes accidents do happen".

As police continued to investigate the cause of the incident, Sydney Skydivers cancelled all jumps on Sunday (July 16) out of respect for the victims of the tandem skydive on Saturday afternoon.

The firm said Mr Low, 29, was on his first tandem skydive with an instructor, aged in his 60s, who had made more than 10,000 jumps in his 30-year career. The instructor was named by local media as Adrian Lloyd.

The firm said in a statement on Facebook that the pair were on a routine leap that "was not especially challenging for a highly experienced instructor".

"The jump was from normal height and it is not yet clear what occurred," the statement said.

"The sport of Skydiving is an outdoor adventure activity and it is as safe as it can possibly be with the advancements in technology, training and safety. We understand there are risks, and unfortunately, sometimes accidents do happen."

The tragedy occurred on Saturday at about 2pm during a routine dive from a height of about 4,200m.

The pair landed on a driveway at a private property about a kilometre from their intended landing point on an open field. The accident occurred at Wilton, a town about 85km south-west of Sydney.

Mr Dustin Leonard, who was part of the skydiving group which included Mr Low, said the flight and jump seemed "very standard". Mr Leonard filmed the group using a GoPro camera before the divers leapt from their plane.

"The whole plane ride, everyone was nice, chipper, nice calm flight, going up," he told Channel Nine.

"We got to altitude, like 13,000 feet, and everything was very standard… It's quite a shock. You knew just by the look on their face, you knew something was wrong."

Sydney Skydivers said it was assisting police, describing the incident as "an extremely unusual event".

"The exact causes are under investigation and as yet are unknown," it said.

"Our sympathies go out to the families and friends of both men as well as those in our skydiving community."

Asked whether it had been in contact with the family of Mr Low, the office of Sydney Skydivers told The Straits Times it was not commenting beyond its Facebook statement.

The firm - the largest skydiving training centre in Australia - said the deaths were the first involving a first-time tandem dive in its 40-year history.

But ABC News reported on Sunday that the firm has been involved in six fatalities in the past 16 years. This included two deaths in 2001 and two in 2012.

The Australian Parachute Federation, which is assisting with the police investigation, said it was looking into possible causes such as equipment failure or human error.

Mr Lloyd was a veteran diver who has participated in record-breaking formation skydives.