An unidentified number of Koreans were injured during an explosion Tuesday in Istanbul, local media reported.

The consulate general in the Eurasian country’s ancient city is examining the incident in the popular tourist hotspot of Sultanahmet, close to the Blue Mosque and Hagia Sophia, but the precise extent of damage remains unknown.

A local tour guide told Yonhap news agency that two Koreans including himself suffered “slight wounds” such as on their fingers and “several” travelers from other countries were killed. ”We heard an enormous blast as I briefed my clients at the square,” the guide was quoted as saying.

According to news reports, witnesses in the vicinity reported a “loud blast” and claimed a suicide bomber detonated a device nearby the Sutanahmet tram stop and Dikilitas, the Obelisk of Theodosius, in the heart of the district, killing some tourists from Germany and elsewhere.

But the exact cause of the explosion was not immediately clear as Turkish authorities have not yet confirmed it.

A slew of ambulances were dispatched to the scene sealed off by police there, the reports noted.

By Shin Hyon-hee (heeshin@heraldcorp.com)