Malaysia’s transport ministry said Thursday that more plane parts have washed up on the same island as a wing part believed — with varying degrees of certainty — to be from missing Malaysia Airlines Flight 370.

Those new items, which the Malaysians described as pieces of windows, seat cushions and aluminum material, will be tested by the same international team of experts who are looking at a piece of a wing that the Malaysians said Wednesday is definitely from MH370.

An Australian agency coordinating the search for the missing airliner, however, says there is no indication so far of any new aircraft debris.

“A great deal of additional material has been handed over to the police” on Reunion island, the Joint Agency Coordination Centre said in a statement. “While this is being examined, so far none of it appears to have come from an aircraft,” the Australian statement.

For a second day, the Malaysian government and officials from other nations trying to determine the fate of the long-missing airliner signaled differing degrees of certainty about its fate.

Since Malaysian Prime Minister Najib Razak announced that the wing part, called a flaperon, is definitely from MH370, other officials have expressed more caution and saying that more testing is needed.

On Wednesday, less than an hour after the Prime Minister’s statement, Paris Deputy Prosecutor Serge Mackowiak used slightly less definitive language. Mackowiak said that there were “very strong presumptions” that the debris from the French island in the western Indian Ocean was from MH370, but certainty was not yet possible.

The Boeing 777, carrying 239 people, disappeared on a flight from Kuala Lumpur to Beijing on March 8, 2014.

The families

The families of those on board say they are angry, frustrated and bewildered by what they’ve been told.

“We do not want to hear guarantees of 99% likelihood from certain authorities,” the Chinese families said in a statement. “We need confirmation of 100% certainty.”

“I was left somewhat confused and, frankly, a little angry and dismayed,” said K.S. Narendran, whose wife was one of the passengers.

“I didn’t hear facts. I didn’t hear the basics. I heard nothing,” he said, “and so it leaves me wondering whether there is a foregone conclusion and everyone is racing for the finish.”

The families of Chinese passengers, the most numerous nationality on the flight, were also unsatisfied.

“I don’t believe this. I don’t!” said Xu Jinghong, whose mother was on board Flight 370. “I am furious and I think this announcement is very irresponsible.”

Mary Schiavo, a CNN aviation analyst, said the families appeared to be stuck in the middle of a “tug of war among nations.”

But Sondra Wood, whose son Philip was on the airliner, said she feels the announcement “is the beginning of closure.”

“We know that it’s definitely in the ocean. It may be a journey or we may never find the plane, but at this point at least we don’t have to wonder, or guess, or fruitlessly hope that they could still be alive,” she told CNN’s “The Lead with Jake Tapper.”

The investigation

Najib said the flaperon matches a Boeing 777, the model of the airplane that disappeared on March 8, 2014, and the characteristics of the piece match the technical specifications provided by Malaysia Airlines for that part of the missing aircraft.

He also said a maintenance seal on the flaperon belongs to MAS, short for Malaysian Airline Systems, as the airline was once called. He added that the paint and a serial number match as well.

Boeing officials have concluded that the part’s technical features — such as its color and the structure of its joints — confirm that it’s from a 777 aircraft, he said.

Drawing on documentation provided by Malaysia Airlines, the French prosecutor said, experts also identified “common technical characteristics” between the flaperon found on Reunion and that of Flight 370. But Mackowiak stopped short of making a definitive link.

The softer language used by the French prosecutor highlights the complex, multinational nature of the investigation into what happened to MH370.

Malaysia Airlines said in a statement that the confirmation announced by Najib, which it described as “a major breakthrough,” had been made jointly by French, Malaysian, Chinese and Australian officials.

But a source close to the investigation told CNN that French and U.S. experts examining the flaperon have not yet found anything that would definitively link it to Flight 370. The American officials involved are from the National Transportation Safety Board.

While it is expected that the wing part will eventually be matched to MH370, the source said that there was so far nothing precise enough for 100% confirmation.

The next steps

The analysis of the flaperon will continue at the specialized lab near Toulouse.

“The experts are carrying out their work promptly in order to provide complete and reliable information as soon as possible to the victims’ families,” Mackowiak said.

But he cautioned that he was unable to specify when the results of the ongoing analysis would be announced.

“On a forensic investigation, which is what’s going on in France, you don’t use the process of elimination and say, well, it must be a flap,” said David Soucie, a CNN aviation analyst. “You have to have forensic proof, which is the samples from the paint, from the metal, to tie it specifically to the aircraft. That’s what they’re waiting for, and that’s what they mean by 100% conclusive.”

Experts have said that investigators may be able to glean clues from the wing debris about Flight 370’s final moments before it is believed to have gone down in the southern Indian Ocean. Did it break apart in midair or hit the water intact?

But neither the French nor the Malaysians made any reference to that aspect of the analysis.

Australian Prime Minister Tony Abbott, whose country is leading the underwater search for the remains of MH370, said Thursday that the Reunion Island discovery “suggests that for the first time we might be a little bit closer to solving this baffling mystery.”

The remnants of a suitcase that were found near the flaperon on Reunion are being sent to a different French lab for examination, Mackowiak said.

The search

Officials on Reunion are continuing to comb the island’s shores for more possible debris from Flight 370.

While the Malaysian official described apparently new debris that was spotted, a journalist on Reunion Island said, citing police, that no debris was reported or handed in Thursday. Police also say that nothing definitive has been turned in during the past week.

But it’s anyone’s guess whether many items from the aircraft are likely to find their way there.

“The problem is the only way for parts of the plane to get to Reunion Island is to continue to float,” Schiavo said. “The flaperon could because there are spaces inside that part that could allow air to be trapped and for it to float.”

But a lot of other potentially buoyant objects — like tennis shoes, bits of luggage and items from the plane’s galley — are likely to have become waterlogged and sunk after long months out in the ocean, she said.

The bigger, heavier parts of the aircraft are likely to have gone down into the depths very quickly.

The Australian-led underwater search for the wreckage and the remains of the people on board is taking place in a large, remote area of the southern Indian Ocean.

Locating the plane’s cockpit voice recorder and flight data recorder, as well as the cockpit itself, is likely to be investigators’ best hope of unlocking the mystery of why it flew dramatically off course and lost communication with air traffic control.

“The finding of wreckage on La Reunion is consistent with our current search area,” Australian Deputy Prime Minister Warren Truss said Thursday. “For this reason, thorough and methodical search efforts will continue in the defined search area.”