In this photo taken from an Indonesian Air Force Super Puma helicopter, portion of the tail of AirAsia Flight 8501 is seen on the deck of rescue ship Crest Onyx after it was recovered from the sea floor on the Java Sea, Saturday, Jan. 10, 2015. Investigators searching for the crashed plane's black boxes lifted the tail portion of the jet out of the Java Sea on Saturday, two weeks after it went down, killing all 162 people on board. (AP Photo/Suharso, Pool)

PANGKALAN BUN, Indonesia - A day after the tail of the crashed AirAsia plane was fished out of the Java Sea, the search for the missing black boxes intensified Sunday with more pings heard.

The signals were detected over an area spanning from 1 kilometre to 4 kilometres (1.6 miles to 2.4 miles) from the location of the jet's rear. Officials cautioned it was too soon to know if the sounds were coming from the cockpit voice and flight data recorders, which detached from the tail of when the aircraft plummeted into the sea Dec. 28, killing all 162 people on board.

"It was detected within a wide area, which needs to be combed by divers," said Nurcahyo Utomo, an investigator with Indonesia's National Commission for Transportation Safety. "Right now, I would not dare to say if it's from the black boxes."

He said the weather allowed work to continue in the morning, but that strong currents and high waves, which generally worsen in the afternoon, could prevent divers from thoroughly searching the area.

However, AirAsia CEO Tony Fernandes expressed optimism by tweeting that while still not confirmed, he was receiving strong information that the recorders may have been found.

On Saturday, search crews had a major breakthrough after two weeks of hunting for victims and wreckage from Flight 8501. The red metal chunk from the tail, with the words "AirAsia" clearly visible across it, was brought to the surface using inflatable balloons.

But the find was tinged with disappointment when the black boxes were not found still attached. Their beacons emit signals for about 30 days until the batteries die, meaning divers have about two weeks left before they go silent.

The debris from the tail was brought up from a depth of about 30 metres (100 feet) and towed to a ship, where it was hoisted onto the deck. The vertical stabilizer was still largely intact, but the attached jagged fuselage was ripped open and tangled by a mess of wires.

The slow-moving search has been hampered by seasonal rains, choppy seas and blinding silt from river runoff.

Suryadi Bambang Supriyadi, operation director of Indonesia's national search and rescue agency, said his top priority remains finding the main section of fuselage, where most of the bodies are believed to be entombed. Several large objects have been spotted in the area by sonar, but they have not yet been explored underwater. So far, only 48 corpses have been recovered.

"This is what the families have been waiting for," he said. "They have been crying for 14 days."

The last contact the pilots had with air traffic control, about halfway into their two-hour journey from Indonesia's second-largest city, Surabaya, to Singapore, indicated they were entering stormy weather. They asked to climb from 32,000 feet (9,753 metres) to 38,000 feet (11,582 metres) to avoid threatening clouds, but were denied permission because of heavy air traffic. Four minutes later, the plane dropped off the radar. No distress signal was issued.

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Associated Press writer Ali Kotarumalos in Jakarta, Indonesia, contributed to this report.

News from © The Associated Press, 2015