Turkey's Ministry of Labor and Social Security launched an investigation into the explosion that killed four people in Tupras' İzmir refinery on Wednesday.
Following the explosion, the Minister of Labor and Social Security Julide Sarieroglu instructed the launch of an investigation in which three chief inspectors and one inspector were assigned to lead enquiries.
In a written ministry statement, it reported that the blast occurred in the morning at the Izmir Tupras refinery where four people lost their lives and two people were injured.
Tupras cited gas entrapment earlier as the cause of the explosion.
The company said that despite all rescue efforts, employees Kemal Sasmazer, Yusuf Kepenek, Mehmet Karademir and Mehmet Dere lost their lives while the treatment of injured Halil Ibrahim Kavlak is ongoing.
Reporting By Ozcan Yildirim
Writing By Murat Temizer