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2 years after Flight 370 vanished, are we closer?

240 white balloons floated skyward from a Kuala Lumpur shopping center as families of those on board Malaysian Airlines Flight 370 gathered to mark the two-year anniversary of the Boeing 777's disappearance.

There were 227 balloons for the passengers, 12 more for the crew and one for the missing aircraft, each drifted away with "MH370: Always remembered in our hearts," written in black ink.

In China, where the tragedy has hit particularly hard, relatives gathered at a temple in Beijing to burn incense and pray.

"My hope is that they will find the plane. I also hope that the Malaysian side will not stop the search and that they will continue until they find the plane. I heard they are going to stop. That cannot happen," Zhang Qian, who lost her husband on the flight, told The Associated Press.

It was the afternoon flight from Malaysia's capital to Beijing, China that took off from Kuala Lumpur International Airport on March 8, 2014, and never arrived.

Based on radar data, investigators know the plane turned sharply as it approached Vietnamese airspace, but all contact was eventually lost off the coast of Thailand.

"I do not think it possible to fully understand how difficult the past two years have been for the friends and families of those on board the aircraft. The sense of loss is something they live with on a daily basis," said Australia's Minister for Infrastructure and Transport, Darren Chester.

The search for the missing jetliner continues, but so far only one confirmed piece of the plane's wing has been found. That "flaperon" washed up on Reunion Island in July, carried across the vast Indian Ocean by the tides.

Within the last week, another possible piece of debris from the airliner was found on the French island, which sits about 1,000 miles off the east coast of Africa.

Before that, a third possible piece of the plane was recovered more than 1,000 miles away, off the coast of Mozambique, by an American who has been searching for the aircraft.

"This is about 239 people and their loved ones who have not seen them for almost two years. And so I want to exercise caution. We don't yet know what this piece is," said Blaine Gibson, who found the triangular piece that experts believe may have come off the horizontal stabilizer on the plane's tail. The words, "NO STEP" are painted on the piece.

"My heart was thumping, there was anticipation, there was excitement, there was feeling. But there was also a caution, saying: 'Hey, we just don't know what this is. There's a responsibility here to do the right thing, take care of it," Gibson told The Associated Press.

The piece will be examined by experts in Australia to determine if it did come from the missing airliner.

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An item found in Mozambique, believed to be a possible piece of debris from Malaysia Airlines Flight 370, in March 2016.
ATSB/Blaine Gibson

Australia is leading the current deep-water search and recovery effort to find the missing airliner, with a goal of completing a 46,000-square-mile search area off the west coast of Australia later this year.

Of the 240 people on board the plane, 153 were Chinese nationals. On the eve of the anniversary, about a dozen families filed lawsuits against the airline, Boeing and engine-maker Rolls Royce.

But the agonizing wait continues.

Jacquita Gonzales, wife of MH370 in-flight supervisor Patrick Gomes, wants the search to continue until the plane is found.

"We are fighting to search on, because our loved ones are not home yet. So how can we say it's the end?" Gonzales asked.

Her daughter, Nicolette Gomez, said "what I want to see is the whole plane. So hopefully we get to see the whole plane. From there we will know what it is like."

In his statement marking the grim anniversary, Chester, the Australian official, tried to reassure the families.

"As we search the remaining 30,000 square-kilometer zone in the days and months ahead, Australia, Malaysia and the People's Republic of China remain hopeful the aircraft will be found," he said. "I assure the family and friends of those on board that their loved ones have not been forgotten and continue to be in our thoughts."

"We remain committed to doing everything within our means to solving what is an agonizing mystery for the loved ones of those who were lost," said Malaysia's Prime Minister Najib Razak in a statement. "On this most difficult of days, our thoughts and prayers are with the families of those who will never be forgotten."

While the search continues, the plane's location remains a mystery -- as does what exactly caused the crash.

Investigators favor the theory that someone altered the plane's course and allowed it to fly until it ran out of fuel, but two years after the Boeing 777 disappeared from radar, that is still just a theory.

"We are no closer to understanding what happened and why it happened," said former Chairman of the National Transportation Safety Board, Mark Rosenker, who is now a CBS News aviation safety consultant.

"Frankly, we aren't that much closer to preventing one of these from happening again," added Rosenker. "We can do better."

Filed by CBS News correspondent Kris Van Cleave in Washington.