At least 4 killed in explosion along popular Istanbul pedestrian walkway

Istanbul — An explosion on one of Istanbul's most popular pedestrian thoroughfares killed four people and injured 38 on Sunday, authorities said.

The cause of the blast on Istiklal Avenue was not immediately clear. Five prosecutors were assigned to investigate the explosion, state-run Anadolu news agency said.

A video posted online showed flames erupting and a loud bang, as pedestrians turned and ran away. Other footage showed ambulances, fire trucks and police at the scene. Social media users said shops were shuttered and the avenue closed down.