Reuters reports that a blast rocked Sultanahmet, a popular tourist district in Istanbul, Turkey.
According to Reuters, witnesses state they heard a loud explosion and it shook the ground.
Photos on twitter showed an overturned car. According to Sabah, a police car flipped over onto the tramway and the tram has been shut down.
Earliest estimates are 10 killed and 15 wounded.
Turkish police have sealed off Sultanahmet Square. A bomb squad is present and they are sweeping the area to search for a second bomb. Helicopters are searching from above.
Police believe the attack to be a single suicide bomber.
No organization has claimed responsibility for the attack at this time.
