Also heard about it. There's is a version there was a pyrotechnics fire (due to the welding) and it caused the blastBeirut blast: Dozens dead and thousands injured, health minister says
The explosion has caused widespread damage, with hospitals struggling to treat all the casualties.www.bbc.co.uk
Terrible explosion in Beirut. The shockwaves from it can be seen in the video in the new story from BBC.