No drones spotted over Paris landmarks overnight

There were no reports of drones over Paris landmarks overnight after two straight nights of the mysterious machines triggered concern and bewilderment in the French capital.

One of the three Al-Jazeera journalists arrested Wednesday for illegally flying a drone — in what appears to be an unrelated incident — will appear in court next week, the Associated Press reported. All three of the journalists were released Thursday, a day after police said they were spotted flying a drone over a park in the western part of the city.

Al-Jazeera said Thursday the journalists — who it did not identify — were released after 19 hours in custody. The news organization said in a statement its staff was working on a story after the nighttime drones raised a number of questions in the city.

"Our staff in Paris were attempting to illustrate a piece to camera on domestic drones which are widely available, while also attempting to cover the recent drone mysteries in Paris and wider security concerns in France," the statement said.

Flying the machines without a license in France is illegal and carries a maximum one-year prison sentence and a $85,000 fine, according to the Associated Press.

The drones have so far confounded police, who are scrambling to figure out who has been operating the machines, which were first seen late last year. So far, no leads have been announced in the bizarre incidents.

Five drone sightings had been reported near the Place de la Concorde, Les Invalides and the Eiffel Tower between 11 p.m. Tuesday and 2 a.m. Wednesday — a repeat of excursions over the iconic Iron Lady and near the U.S. Embassy the previous night, French news agency AFP reported.

The flights come amid tightened security in the wake of last month's terrorist attacks that left 17 dead in the capital.

Contributing: Mary Vidon