A French ship has detected signals deep under the Mediterranean Sea, believed to be from the black boxes of EgyptAir Flight MS804. The plane crashed last month, killing all 66 passengers and crew on board.

Citing a statement from Egypt’s investigation committee, the Civil Aviation Ministry said the signals were received from the French vessel ‘Laplace.’

France’s Bureau d’Enquêtes et d’Analyses (BEA) also confirmed that a signal has been detected from one of the black boxes. The BEA is the French body responsible for the investigation of civil aviation accidents.

The investigation committee said in a statement that the search for the black boxes is intensifying ahead of the expected arrival of a separate vessel from the Mauritius-based Deep Ocean Search, which will aim to retrieve the devices. That ship is expected to arrive within a week.

Locator pings emitted by flight data and cockpit voice recorders, known as black boxes, can be detected from deep underwater.

The Airbus A320 crashed on May 19, around 170 kilometers (105 miles) from the Egyptian coast in the Mediterranean sea. The plane had taken off from Charles de Gaulle Airport in Paris.

The plane was carrying 66 people, which comprised of 56 passengers and 10 crew members. Of the passengers, 30 were Egyptian, 15 French and two Iraqi, with one from each of Algeria, Belgium, Britain, Canada, Chad, Kuwait, Portugal, Saudi Arabia, and Sudan.

The search for the aircraft has been narrowed to a five kilometer (three mile) area in the Mediterranean.