A car bomb struck an armoured police vehicle in the Turkish city of Diyarbakir, killing three people and wounding at least 45, the governor's office said in a statement.
The explosion went off in the district of Baglar in the centre of the city, the state-run Anatolia news agency said.
Explosives in the vehicle were detonated from a distance as the police van passed, wounding 12 police officers, the statement added.
Five of the wounded were inmates being moved while under police custody, a security source said.
Al Jazeera's Zeina Khodr, reporting from Gaziantep near the Turkey-Syria border, said the Turkish government has labelled it a "terrorist attack" and the wounded included police officials as well as civilians.
"In March, seven policemen were killed in a similar attack, a car bomb targeting the police, and even today the police were targeted in another town," she said.
Parts of Diyarbakir and other towns in the region bordering Syria, Iraq and Iran have seen intense security operations since conflict between the state and PKK re-ignited last July.
Earlier on Tuesday, two police officers were killed while attempting to defuse a roadside bomb in the eastern province of Van, Anatolia news agency said.
Turkey's southeast has been rocked by waves of violence since a ceasefire between the PKK and the government collapsed last July.
The PKK has been fighting against the Turkish state since 1984, initially for Kurdish independence, although it now presses for greater autonomy and rights for the country's largest ethnic minority.
Source: Al Jazeera and agencies