The attack took place on the street where the local governor's office is located and hit the police vehicle as it passed, the local mayor, Burhanettin Kocamaz, told broadcaster Haberturk.
Images from NTV showed smoke billowing from the area, in Mersin's Yenisehir district. Ambulances, police and fire trucks were sent to the site of the attack, security sources said.
No one immediately claimed responsibility for the bombing. The government's main spokesman, Deputy Prime Minister Bekir Bozdag, said it was a terrorist attack. Kurdish militants frequently target police vehicles and transports vans.
"There was a bomb attack on a police vehicle in a terror attack in Mersin. The event is still fresh, it is not possible for me to give exact numbers at the moment," Bozdag said.
"Turkey's battle against terror will continue under any circumstances in a strong and determined way."
Turkey is battling a three-decade insurgency in its mainly Kurdish southeast. The militant Kurdistan Workers Party (PKK) frequently carries out bomb attacks on security forces in the southeast and elsewhere.
The PKK is considered a terrorist organisation by the United States, Turkey and the European Union. More than 40,000 people, most of them Kurds, have died since it first took up arms against the state.
Smoke rise after the explosion. Picture: Social media
Twelve people were wounded when a bomb hit a police vehicle in Turkey's southern Mersin province on Tuesday, broadcaster NTV said, an attack authorities described as the work of terrorists.
