Europe 1 with AFP 11:29 a.m., April 20, 2022, modified at 11:30 a.m., April 20, 2022

A bomb, placed under an electric pole at the edge of a road, exploded as the bus carrying the prison guards passed.

The attack also injured four people, including one in serious condition, the governor said.

The targeted bus was carrying around 30 guards and the explosion was "visibly triggered" by a remote-controlled system, the governor added.

A bomb attack targeting a bus carrying prison guards in Bursa, an industrial city in northwestern Turkey, left one dead and four injured, Turkish authorities announced on Wednesday.

A bomb, placed under an electricity pole on the side of a road, exploded as the bus carrying the prison guards passed, causing "a martyr", Bursa governor Yakup Canbolat told the private Turkish channel NTV.

The attack also injured four people, including one in serious condition, the governor said.

The targeted bus was carrying around 30 guards and the explosion was "visibly triggered" by a remote-controlled system, the governor added.

"Operations to arrest those responsible are ongoing," Turkish Interior Minister Süleyman Soylu tweeted.

The attack has not been claimed.

Bursa-Mudanya yolunda infaz koruma memurlarının geçişi esnasında bir EYP'nin uzaktan kumandayla patlatılması sonucu 1 infaz koruma memurumuz Şehit oldu.



Faillerin yakalanması için çalışmalar sürüyor.



Şehidimize Allah'tan rahmet, yaralı personelimize acil şifalar diliyorum.

— Suleyman Soylu (@suleymansoylu) April 20, 2022

Turkish offensive against the PKK since Monday

Turkey suffered a wave of attacks in 2016, claimed by the jihadist group Islamic State and by the Kurdistan Workers' Party (PKK), an organization described as "terrorist" by Ankara and its Western allies.

This attack comes as Turkey has launched since Monday an air and ground offensive against the PKK, which has bases and training camps in northern Iraq.

Former capital of the Ottoman Empire before Constantinople, Bursa, known for its silks, is home to one of Turkey's main industrial areas, particularly for automobiles and textiles.