ISTANBUL, Turkey (AP) – A huge fire engulfed the cargo section of Istanbul’s Ataturk International Airport on Wednesday, temporarily disrupting air traffic and causing thousands to flee nearby terminals.

Three people were treated for smoke inhalation, said Deputy Gov. Fikret Kasapoglu.

Authorities gave various explanations for what caused the blaze, which billowed black smoke 100 feet into the air at Turkey’s busiest airport before it was brought under control.

Kasapoglu said a short-circuit was to blame, while another deputy governor, Vedat Muftuoglu, told CNN-Turk television at the scene that a spark from a welder’s torch caused the fire.

Muftuoglu said there was no sign the blaze was terrorism-related.

Kasapoglu assured passengers that there was no danger and flights were taking place, although with delays.

Private NTV television said the fire began in a section where fuel depots were located.

Planes dropped water onto the flames, and airport authorities said the fire was being tamed. A firefighter atop a tall ladder poured a stream of water on the blaze.

“The fire is under control and we’re taking precautions to prevent it from spreading to passenger terminals,” said Baris Tozar, the undersecretary of the Transportation Ministry.

“There are no problems concerning flight security,” Tozar added.

Airport director Irfan Balta said planes had been successfully moved away from the fire.

The two-story cargo building, located near a hangar housing military aircraft, is used to store international freight arriving in Istanbul. Gov. Muammer Guler of Istanbul said parts of the building collapsed and there was “great financial damage.”

Hundreds of uniformed cargo workers who escaped the building in a panic anxiously watched the blaze.

“A huge black cloud came, it smelled like cables burning, the roof started burning,” said cargo worker Omer Toplar, adding that there was no explosion.

Sky Turk television showed a female airport worker in uniform, apparently affected by the smoke, being treated by medics. Firefighters were seen moving barrels containing chemicals to a safe area.

Millions of tourists pass through the airport each year to reach Turkish resorts on the Mediterranean or Aegean coast.

Radical Islamic, leftist and Kurdish militants are active in Istanbul and Kurdish militants recently claimed responsibility for a huge fire at an Istanbul factory.