New Delhi, Sept. 19 -- A large plume of black smoke was visible near Riyadh's King Khalid International Airport on Saturday (September 19) after explosions were heard in the Saudi capital, hours after authorities issued alerts warning of a potential aerial threat.

Reuters reported a huge column of black smoke rising near the airport, with the airport highway, terminal buildings and other facilities visible in the foreground. Flames were also seen rising from behind what appeared to be fuel tanks.

An AFP journalist at the scene reported seeing firefighters attempting to extinguish a burnt-out fuel tank bearing the logo of Saudi oil giant Aramco.

Saudi authorities did not immediately say what caused the smoke or the explosions.

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