A pipe bomb exploded in downtown Istanbul, Turkey, on Tuesday leaving at least five people severely injured. The bomb was placed and detonated on a busy highway overpass near a crowded subway station at the height of the Istanbul rush hour.

The five injured were taken to a nearby hospital as the bomb explosion caused some concern with the rush hour commuters. There has been a rash of bombings in Turkey of late and the populace have been feeling the stress of it all, according to The New York Times. The bomb was left near a central and busy subway station on the European side of the city and was specifically detonated to coincide with the rush hour as the bomber apparently wanted to inure or kill as many people as he could.

Local Istanbul news media reported that the bomber exploded the pipe bomb only a few seconds after an entire busload of police officers had passed by his position. Authorities believe that the bomber knew the police were coming and that the bus load of police officers had been the bombers target.

The government authorities stated that there were several vehicles involved in the bomb explosion and a bus and at least one car was heavily damaged by the blast. The government ordered the police to the scene dressed in full riot gear with shields in the event that there were more bombs. The police sealed off the area and began their investigation.

While no one has claimed responsibility, Turkish authorities are casting a wary eyes at the Kurds. The Kurds have been fighting the Turks for a long time in an effort to establish their own separate country in the southeastern section of Turkey. Hundreds of people were killed over the summer as armed Kurdish soldiers engaged in several battles with Turkish forces.

Two bombings in Turkey, one in July and another in the capital of Ankara in October, had left 130 dead. The Islamic State claimed responsibility for both of the bombings.