This story was updated most recently at 12:35 p.m. ET on April 5.

This could be it.

A Chinese ship searching for the missing Malaysia Airlines plane has detected a pulse signal on the same frequency used by black boxes, according to China's state-run Xinhua News Agency.

The Haixun 01 heard the ping with a frequency of 37.5 kHz about 1,050 miles off Perth, Australia in the southern Indian Ocean, which is significant because it's not a sound of nature or animals in the ocean — it's man made. Two other ships that searched the area on Saturday, the Royal Navy's HMS Echo and the Royal Australian Navy's Ocean Shield, reported no findings.

A CCTV News reporter on board the ship said searchers first detected the frequency Friday, and then again on Saturday. It lasted for 15 minutes before the signal was lost.

This could mean the Chinese are using equipment in the search not previously disclosed to the Australian authorities, according to Mary Shiavo, former inspector general of the United States Department of Transportation.

The signal was reportedly picked up at 25 degrees south latitude and 101 degrees east latitude, and comes as a Chinese plane reported spotting a number of white objects floating in the search area.

Australian Defense Minister David Johnston warned that even if this turns out to be Flight 370's black box — and it's not clear if it is — it could take weeks to find its location on the sea bed. "There's a huge chance of false positives here," he warned. The CCTV News reporter on board the ship said rescuers believe the signal is not exclusive to black boxes, so it could be from another piece of equipment.

Australian Air Chief Marshal Angus Houston, head of the Joint Agency Coordination Centre, said reports that the Haixun 01 had detected electronic pulse signals related to Flight 370 could not be verified at this time.

"I have been advised that a series of sounds have been detected by a Chinese ship in the search area. The characteristics reported are consistent with the aircraft black box. A number of white objects were also sighted on the surface about 90 kilometres from the detection area. However, there is no confirmation at this stage that the signals and the objects are related to the missing aircraft," Houston said. "Advice tonight from the Australian Maritime Safety Authority's Rescue Coordination Centre (RCC) and the Australian Transport Safety Bureau is that they cannot verify any connection to the missing aircraft."

"The RCC in Australia has spoken to the RCC in China and asked for any further information that may be relevant," he added. "The deployment of RAAF assets to the area where the Chinese ship detected the sounds is being considered."

The Chinese government informed Malaysian Prime Minister Najib Razak of the development earlier today.

Up to ten military planes, three civil jets and 11 ships searched the area on Saturday. The Australian Transport Safety Bureau said it continues to refine the search area where the aircraft reportedly entered the water “based on continuing ground-breaking and multi-disciplinary technical analysis of satellite communication and aircraft performance, passed from the international air crash investigative team comprising analysts from Malaysia, the United States, the UK, China and Australia.”

The plane has been missing since March 8 when it vanished from the skies, as it entered Vietnamese airspace — and hasn't been heard from since. There were 239 people on board, and their families say they want answers.

The search to find the plane's black box is running out of time. Batteries in the flight recorders only last 30 days, which means the black box could go silent as soon as Monday. If that happens, we might never know what happened to Malaysia Airlines Flight 370.

It would forever be one of modern aviation's biggest mysteries.

This story is breaking. We'll continue updating it as new details become available...

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