Last Updated May 27, 2016 6:23 AM EDT
CAIRO -- The chief investigator in the EgyptAir plane crash that killed all 66 people on board last week has said search teams in the Mediterranean have picked up a beacon believed to be from the doomed aircraft.
Ayman al-Moqadem said the beacon signal had narrowed down the search to a 3-mile radius. He insisted, however, that it did not mean the flight data and cockpit voice recorders -- the so-called "black boxes" -- had been found.
Al-Moqadem said finding the boxes requires highly sophisticated technology. He said the signal that was picked up comes from one of the devices on the plane transmitting its location. He spoke to reporters on Thursday.
He did not, however, say when the signal was detected, and has has become customary with new information from Egyptian officials relating to the crash, it was almost immediately challenged by other sources.
The Reuters news agency quoted anonymous officials "close to the investigation" as saying no new signals from the the plane had been detected "since day one."
The conflicting information could not immediate be reconciled.
Speaking Wednesday to CBS News correspondent Holly Williams in Cairo, Egypt's Minister of Civil Aviation said "nothing has been ruled out" in determining the cause of the EgyptAir flight 804 crash.
"It could have been anything, but mechanical failure is... one of four or five assumptions or possibilities that might have happened to the aircraft," Minister Sherif Fathy said.
He told Williams the possible causes for the downing of the flight include mechanical failure, a fire on board, an electrical problem, or an act of terrorism.
"It could have been many other things," Fathy said. "Nothing has been ruled out. And it's too early for that, Holly, the investigation has to really continue and we have to locate the data boxes (black boxes) before we say anything."
France's air accident investigation agency has said a French naval ship specialized in underwater searches will help search for the black boxes.
The flight and voice recorders still need to be retrieved, and as Fathy points out, once they are retrieved it could take a period of months to analyze the data on them.
The chief of EgyptAir said this week that Egypt has contracted two foreign companies to help locate the flight data recorders in Mediterranean. They are believed to sit as deep as 10,000 feet on the seabed.