An explosion tore through Qatar’s key natural gas export terminal Sunday night as workers tried to resume operations there after Iran bombed it during the war, causing a fire that hurt at least 54 people as another 18 were still missing hours later.

The blast at the Ras Laffan industrial area could cause further chaos in global energy markets, particularly as Qatar remains one of the world’s top natural gas producers. Qatar shut down its production after Iran’s chokehold on the Strait of Hormuz meant it couldn’t get shipments out to its clients.

With Iran loosening its grip on the strait as negotiations continue over a permanent end to the war, Qatar began work to try to restart its export terminal. On Sunday night, that work sparked an explosion and fire at the Barzan gas supply facility, the state-run firm QatarEnergy said.

The scale of the damage remains unknown after the blast, with officials initially saying only a few people had been hurt. But hours later, Qatar’s Interior Ministry offered the far-greater casualty figures.