Reports: Explosion rocks Turkish city of Bursa

An injured person sits in an ambulance after a suicide bomb attack outside the historical tourist destination at Ulu Cami in Bursa, Turkey, Wednesday, April 27, 2016. The office of the governor of Bursa said in a statement carried by the state-owned Anadolu Agency that a woman believed to be a suicide bomber blew herself up. (IHA agency via AP ) TURKEY OUT (The Associated Press)

Security forensic officials work after an explosion outside the historical Ulu Cami in Bursa, Turkey, Wednesday, April 27, 2016.Turkish officials say a suicide attack has hit the northwestern city of Bursa, a popular tourist destination. A security official told The Associated Press the attack Wednesday was carried out by suicide bomber. (DHA agency via AP ) TURKEY OUT (The Associated Press)

Security officials secure the area after an explosion outside the historical Ulu Cami in Bursa, Turkey, Wednesday, April 27, 2016. Turkish officials say a suicide attack has hit the northwestern city of Bursa, a popular tourist destination. A security official told The Associated Press the attack Wednesday was carried out by suicide bomber. (IHA agency via AP ) TURKEY OUT (The Associated Press)

Turkish media reports say an explosion has rocked a major city in northwestern Turkey.

The private Dogan News agency says the explosion hit near the Grand Mosque of Bursa and broadcast footage shows people fleeing the area.

NTV television says three people were wounded by the blast. The state-run Anadolu Agency says ambulances and fire brigades have been deployed to the scene.

There was no immediate word on the cause of the explosion.

Turkey has recently been hit by several attacks by the Islamic State group and Kurdish rebels but also on occasion witnesses explosions related to natural gas malfunctions.

The United States on Tuesday issued a new warning to its citizens about "credible indications" of terrorist threats at tourist areas in Turkey.