Fears bomb behind blast near Istanbul subway

The explosion was caused by a bomb, Reuters cited the head of the Bayrampasa district as saying.

There are conflicting reports about the number of people injured. Turkish broadcaster NTV has reported that six people have been injured in an explosion of unknown origin.

Social media users have posted various photos of people evacuating the subway station, while local media said that trains have been stopped at one of the stations.

NTV also reported that the explosion may have been caused by a bomb on an overpass. According to other reports, the explosion was caused by a power transformer blowing up.

The explosion was heard in several districts of Istanbul, residents of the city said on Twitter. Local media reported that fire services and ambulances were sent to the site of the incident.

Electricity was cut off in Bayrampasa and the surrounding district, according to HaberTürk TV. 

Istanbul police said that the cause of the blast is still unknown, adding that an investigation into the incident has been launched, Reuters reported.