TOP: On Feb. 9, French company Malou Tech’s “Army” speed drone, mounted with a Go pro Hero3, performs during a demonstration flight in La Queue-en-Brie, east of Paris. (Francois Mori/AP) BOTTOM LEFT: An aerial file photo taken Jan. 11 shows the Eiffel Tower. (Kenzo Tribouillard/AFP via Getty Images) BOTTOM RIGHT: A July 9, 2012, photo from a French army Transal aircraft shows the Invalides in Paris during a rehearsal flight ahead of the traditional July 14 military parade. (Guillaume Baptiste/AFP via Getty Images)

Unidentified drones were spotted flying over Paris for the second night in a row, French police say.

The unmanned aircraft were spotted near the U.S. Embassy, the Eiffel Tower and several major roads leading out of the capital in at least five instances Tuesday night and early Wednesday morning, according to Agence France-Presse.

The sightings are the latest episode in a months-long mystery that has baffled French police. The tiny, unexplained drones have been haunting some of the country’s most sensitive locales — power plants, government buildings, a bay in Brittany where nuclear submarines are housed — sparking unease in a nation already on high-alert after January’s deadly attacks on a satirical newspaper office and kosher grocery store in Paris.

And even after months of sightings, officials have few leads as to the drones’ operators and purpose. Police say they could be scouts for a sinister criminal operation or part of a benign but ill-conceived prank. Because small drones can be bought easily and cheaply in France, nearly anyone could be responsible for them.

A Paris prosecutor called for a police investigation of the drone appearances Tuesday, as French law prohibits flying the vehicles in urban areas, a spokesman told the Wall Street Journal.

The sightings date back to October, when guards for the state-run power company reported spotting the aircraft buzzing near a nuclear plant about 100 miles from Paris. Authorities confirmed that the drones were civilian or commercial, not military, and labeled them an “organized provocation” aimed at “disrupting the surveillance chain and protection of these sites,” the New York Times reported at the time.

Three people were arrested in association with the October incident but were released after authorities determined that they were simply “harmless model enthusiasts.”

And the unexplained flyovers continued. In January, a drone was spotted zipping over the Elysee Palace, home to French President François Hollande, just a week after the Paris terror attacks.

The BBC reported that these latest flights were captured on film and will be analyzed by a team of 10 investigators convened in the wake of the initial sightings. It added that analysts believe authorities are more more likely to be concerned that a member of the public could be hit by a drone than by the risk to security.

A spokesman for France’s Gendarmerie Nationale declined to comment on the drone sightings.

Read more:

Trial of ‘American Sniper’ Chris Kyle’s killer: Why the insanity defense failed

Remembering when ‘Parks and Recreation’ was terrible

Botched newspaper exposé of HPV vaccine’s ‘dark side’ reveals dark side of news business

Mysterious East Coast flooding caused by ‘unprecedented’ surge in sea level

State Department official charged with soliciting a juvenile for sex