No group has so far claimed responsibility for the attack
At least 10 people were wounded on Thursday when a bomb concealed in a motorbike exploded near a police station in Istanbul, local authorities said, in the latest attack to strike Turkey's increasingly tense largest city over the last year.
The explosion rocked the district of Yenibosna on the European side of Istanbul, close to the city's main Ataturk International Airport.
"Five citizens were injured, one of them seriously, according to initial findings, after a motorbike bomb exploded," Istanbul governor Vasip Sahin wrote on his official Twitter account.
Many ambulances were dispatched to the scene, CNN-Turk television reported. 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.
"It was a serious trauma. I cannot describe in words," one witness Metin Alev told CNN-Turk, who was a few dozen metres from the scene. "There's dust everywhere."
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 hit Istanbul on three occasions.
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 carried out by a bomber linked to IS militants at a Kurdish wedding in the southeastern city of Gaziantep.
The country is also still reeling from a failed 15 July 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.
The Turkish military has stepped up operations against Kurdish militants after the rupture in 2015 of a fragile ceasefire and there has been a dramatic surge in violence that so far shows no sign of ending.
The outlawed Kurdistan Workers' Party (PKK), designated as a terror group by Turkey and its Western allies, generally concentrates its attacks in the southeast of the country.
However its activists have on occasion carried out attacks in Istanbul.
A splinter group of the PKK, the Kurdistan Freedom Falcons (TAK), claimed a June car bombing in the centre of Istanbul that killed seven police and four civilians.
Other groups who have carried out bombings in the capital include the Revolutionary People's Liberation Party/Front (DHKP-C) and the Marxist-Leninist Communist Party (MLKP).