A bomb explosion wounded 10 people in and around a Turkish police bus near the ruling party headquarters in Istanbul early Thursday, Anatolia news agency reported citing police.
"It appears to be a remote-controlled bomb that went off as a duty vehicle with 21 policemen on board drove by," Istanbul police chief Huseyin Capkin was quoted as saying by the agency.
Governor of Istanbul Huseyin Avni Mutlu said the bomb was composed of plastic explosives, according to Anatolia.
The blast hit close to the offices of the ruling Justice and Development Party (AKP), said the private NTV news channel. Istanbul police believes the bomb was carried on a motorcycle, it said.
The wounded were hospitalized with minor injuries, none of them critical, Capkin said.
Witnesses in nearby vehicles reported a strong blast that rocked their cars, causing panic and some damage to the road itself.
Police blocked access to the blast zone, fearing a second explosion.
Several outlawed armed groups -- Kurdish, Islamist and leftist extremist -- have carried out bomb attacks in Istanbul in the past.
In May 2011, a bomb blast near a bus stop injured eight people in Etiler, an upscale district in Turkey's largest city.
Last September a powerful bomb rocked the centre of the capital Ankara, killing three people and wounding at least 15.