Ten people were killed and fifteen others were wounded after a large explosion rocked a central Istanbul square on Tuesday, a statement from the Istanbul governor's office said.

Investigations were being conducted into the type of explosive which caused the blast and those responsible, the governor's office statement said.

The incident took place on Sultanahmet Square. It occurred close to the Sultanahmet tram stop and Dikilitas, the Obelisk of Theodosius, in the heart of Istanbul’s tourist district, local media reported.

According to Dogan News, there are a number of people killed and injured at the scene. They report at least two injured were taken to hospital.

Erdem Koroglu, who was working at a nearby office at the time of the explosion, told NTV he saw several people lying on the ground following the blast.

“It was difficult to say who was alive or dead,” Koroglu said. “Buildings rattled from the force of the explosion.”

One woman who works at a nearby antiques store told Reuters that the explosion was very loud.

"We shook a lot. We ran out and saw body parts," she said.

"We're taking precautions against a second explosion," a police officer said.