The bomb exploded at an intersection in Bayrampasa district on the European side at around 6.00 p.m. local time (1600GMT) during rush hour. One person was slightly injured, the province’s governor Vasip Sahin said.

One of the injured man, Adnan Yalcin, 36, is in stable condition, according to hospital sources.

The explosion cracked the windows of the train and passengers on board were evacuated onto the tracks.

Although Istanbul’s metro is largely underground, it runs above ground in some places, including around Bayrampasa.

The Crime Scene Investigation squads confirmed that the blast occurred after a roadside bomb exploded.

The police suspect the bomb was set for a riot police vehicle, which passed by just before the blast.

It is still unknown who, or which group, planted the bomb. Istanbul police, backed by a helicopter, are currently searching for a suspect seen at the site.

“We are evaluating all the possibilities,” governor Sahin said.

“As the incident occurred in a crowded place, it appeared in the media as if it was a big explosion, but there are no victims, fortunately,” he added.