KUALA LUMPUR, Malaysia -- Australian rescue officials say a search in the southern Indian Ocean for possible objects from the missing Malaysia Airlines plane has ended for the day but will resume in the morning.
A statement from the Australian Maritime Safety Authority says four planes searched an area about 1,550 miles southwest of Perth on Thursday.
The four planes were checking to see if two large objects spotted in satellite imagery bobbing in the ocean were debris from Fight 370 that disappeared March 8 with 239 people on board.
The statement says the search covered an area of 8,800 square miles on Thursday.
One of the objects they were searching for was almost 80 feet in length and the other was 15 feet.
Officials described the debris sighting as "probably the best lead" so far in finding the missing Malaysia Airlines flight.
Australian authorities said the first plane to reach the area was unable to locate the debris through rain and clouds, but that other planes would continue the hunt. The Australian Maritime Safety Authority said there was limited visibility because of the weather, but did not give details.
There could be other objects in the area, a four-hour flight from Australia's southwestern coast, said John Young, manager of the authority's emergency response division.
"This is a lead, it's probably the best lead we have right now," Young said. He cautioned that the objects could be seaborne debris along a shipping route where containers can fall off cargo vessels, although the larger object is longer than a container.
Young told a news conference in Canberra, Australia's capital, that planes had been sent to the area about 2,500 kilometers (1,550 miles) southwest of Perth to check on the objects. He said satellite images "do not always turn out to be related to the search even if they look good, so we will hold our views on that until they are sighted close-up."
News that possible plane parts had been found marked a new phase in the emotional roller coaster for distraught relatives of the passengers, who have criticized Malaysia harshly for not releasing timely information about the plane. While they still hope their loved ones will somehow be found, they acknowledged that news of the find could mean the plane plunged into the ocean.
"If it turns out that it is truly MH370 then we will accept that fate," said Selamat Bin Omar, the father of a Malaysian passenger on the jet, which carried mostly Chinese and Malaysian nationals.
But he cautioned that relatives still "do not yet know for sure whether this is indeed MH370 or something else. Therefore we are still waiting for further notice from the Australian government."
Malaysian Defense Minister Hishammuddin Hussein told a news conference Thursday that "for all the families around the world, the one piece of information that they want most is the information we just don't have the location of MH370."
Young said visibility was poor and may hamper efforts to find the objects. He said they "are relatively indistinct on the imagery ... but those who are experts indicate they are credible sightings. The indication to me is of objects that are a reasonable size and probably awash with water, moving up and down over the surface."
Military planes from Australia, the U.S. and New Zealand have been searching in a region over the southern Indian Ocean that was narrowed down from 600,000 square kilometers (232,000 square miles) to 305,000 square kilometers (117,000 square miles).
Young said the depth of the ocean in the latest area, which is south from where the search had been focused since Monday, is several thousand meters (yards). He said commercial satellites had been redirected in the hope of getting higher resolution images. He did not say when that would happen. The current images are not sharp enough to determine any markings.
The Australian Maritime Safety Authority released two images of the whitish objects floating on or just under the surface. The images were taken March 16, but Australian Air Commodore John McGarry said it took time to analyze them.
"The task of analyzing imagery is quite difficult, it requires drawing down frames and going through frame by frame. The moment this imagery was discovered to reveal a possible object that might indicate a debris field, we have passed the information from defense across to AMSA for their action," he said.
The AMSA said on their official Twitter account that the crew of a P3 Orion plane was not able to spot the objects Thursday through limited visibility but that the search would continue.
In a sign that officials expect the search for the objects to take some time, AMSA said a C-130 Hercules plane was sent to drop marker buoys in the area. "They will provide an ongoing reference point if the task of relocating the objects becomes protracted," it said in a statement.
Hishammuddin said the satellite images, "while credible, still must be confirmed."
Some analysts said the debris is most likely not pieces of Flight 370. "The chances of it being debris from the airplane are probably small, and the chances of it being debris from other shipping are probably large," said Jason Middleton, an aviation professor at the University of New South Wales in Sydney.
The area where the debris was spotted is about halfway between Australia and desolate islands off the Antarctic.
The hunt for the Boeing 777 has been punctuated by several false leads since it disappeared above the Gulf of Thailand.
Oil slicks that were spotted did not contain jet fuel. A yellow object thought to be from the plane turned out to be a piece of sea trash. Chinese satellite images showed possible plane debris, but nothing was found.
But this is the first time that possible objects have been spotted since the search area was massively expanded into two corridors, one stretching from northern Thailand into Central Asia and the other from the Strait of Malacca down to southern reaches of the Indian Ocean.
Hishammuddin also made clear that although international search efforts are continuing in both on land and sea in the northern and southern hemispheres, the effort is mostly concentrated south of the equator over the vast Indian Ocean.
Out of a total of 29 aircraft, 18 ships and six ship-borne helicopters deployed in the operation, only four aircraft are now scouring the north.
Norwegian cargo vessel Hoeegh St. Petersburg has been rerouted and arrived at the area in the Indian Ocean where the possible wreckage was spotted, Haakon Svane of the Norwegian Shipowners' Association told The Associated Press.
"It did so at the request of the Australian maritime authorities and it is currently taking part in the search operations," Svane said.
The ship, which transports cars, was on its way from South Africa to Australia when it was rerouted.
Flight 370 disappeared on a night flight from Kuala Lumpur to Beijing. Malaysian authorities have not ruled out any possible explanation, but have said the evidence so far suggests the plane was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.
Police are considering the possibility of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or anyone else on board.
Malaysian authorities have said that files were deleted Feb. 3 from the home flight simulator of the missing plane's pilot, Zaharie Ahmad Shah, and Hishammuddin said he had no new information on efforts to recover those files.
The FBI has joined forces with Malaysian authorities in analyzing deleted data on the simulator. It was not clear whether investigators thought that deleting the files was unusual. They might hold hints of unusual flight paths that could help explain where the missing plane went, or the files could have been deleted simply to clear memory for other material.
Gelineau reported from Sydney, Australia. Associated Press writers Rod McGuirk and Todd Pitman in Kuala Lumpur, Nick Perry in Wellington, New Zealand, and Jan M. Olsen in Copenhagen, Denmark, contributed to this report.