Story highlights "The detection of this signal is a first step," a French official says

Investigators say they've confirmed signals are from one of "black boxes" from EgyptAir Flight 804

Cairo (CNN) A French naval vessel has detected underwater signals from one of EgyptAir Flight 804's so-called black boxes, investigators said Wednesday.

Specialized locator equipment on board the French vessel La Place detected signals from the seabed in the Mediterranean Sea, the Egyptian investigative committee said in a statement.

The director of the BEA, France's air accident investigation agency, later said it had confirmed the signals were from one of the recorders on the plane.

"The signal of a beacon from a flight recorder could be detected. ... The detection of this signal is a first step," BEA Director Remy Jouty said in a statement, according to an agency spokesman.

The Airbus A320, which had 66 people aboard, crashed in the Mediterranean on May 19 on a flight from Paris to Cairo.