Istanbul, Turkey (CNN) -- Turkish Prime Minister Recep Tayyip Erdogan said Wednesday one policeman was killed and another injured when his convoy was attacked on its way to a campaign rally.
Erdogan was not in the convoy at the time of the attack and was airlifted to his next stop in a helicopter, NTV news reported.
The attack happened in northern Turkey, between the cities of Kastamonu and Cankiri, where the prime minister had a campaign event.
A bomb exploded in front of the police convoy escorting the ruling Justice and Development (AK) Party bus after it made a stop in Kastamonu.
Addressing a rally later in Amasya, Erdogan expressed his sorrow about the death, and blamed the attack on separatist groups.
"These dark minds who do not believe in democracy's struggle, these terrorists, these separatist forces believe they can only achieve results this way instead of through the ballot box," the prime minister said.
Erdogan is continuing his election campaign tour for the upcoming national parliamentary elections slated for June 12.
CNN's Ivan Watson, Yesim Comert and Talia Kayali contributed to this report.