title: Blast at Tupras refinery in Turkey kills four, production unaffected
text: ISTANBUL (Reuters) - An explosion in a storage tank at a Tupras refinery in the western Turkish province of Izmir on Wednesday killed four people but had no impact on production, the company said. Tupras said in a statement that the explosion occurred following maintenance work on Wednesday morning.  Television footage showed black smoke rising from the site of the blast. 