A suspected car bomb on Thursday exploded near a police station in Istanbul, leaving at least five people wounded, Turkish television reported.
The explosion rocked the district of Yenibosna on the European side of Istanbul, close to the city's main international airport, CNN-Turk television reported.
Many ambulances were dispatched to the scene, it added. Television pictures showed several cars wrecked and shards of glass scattering the ground after the blast.
Witnesses told CNN-Turk that they heard a powerful explosion as well as gunshots. Turkish police sealed off the area on suspicion of a possible second blast.
The force of the blast blew out the windows of the police station.
Five people were wounded, one of them seriously, the television reports said.
Witnesses also said one vehicle was seriously damaged, raising the prospect that it was a car bomb attack, CNN-Turk said.
Turkey has already been hit by a bloody year of militant attacks in its two biggest cities that have left dozens of people dead and put the country on a high security alert.
Kurdish militants have twice struck in Ankara in deadly attacks, while suspected Islamic State (IS) suicide bombers have on three occasions struck in Istanbul.
In June, 47 people were killed in a triple suicide bombing and gun attack at Istanbul's Ataturk airport, with authorities pointing the finger at IS.
Fifty-seven people, 34 of them children, were killed in August in a suicide attack blamed carried out by a bomber linked to IS jihadists at a Kurdish wedding in the southeastern city of Gaziantep.
The country is also still reeling from a failed July 15 coup blamed on the US-based Islamic preacher Fethullah Gulen that has been followed by a relentless purge of his supporters from all state institutions.
There was no immediate indication who could be behind the latest blast.