A large blast Tuesday, August 4, in the Lebanese capital, Beirut, has killed at least 145 people and injured more than 5,000 others. 2,750 tonnes of ammonium nitrate was stored unsafely in a warehouse for six years in the port of Beirut. A fire at the warehouse generated the blaze. There were two explosions, a smaller one that was followed seconds later by a larger blast that destroyed huge swathes of the city. All the buildings around here have collapsed. The blast was heard 240km (150 miles) away on the island of Cyprus in the eastern Mediterranean. In Beirut was absolute chaos. The extent of the damage is extreme. The ammonium nitrate, used many times as agricultural fertiliser, is highly explosive when it comes into contact with fire. Exploding, it can release toxic gases including nitrogen oxides and ammonia gas. Prime Minister Hassan Diab called the blaze a catastrophe and said those responsible must be held to account. Lebanon’s prime minister also called for international help. President Aoun declared a three-day mourning period, and said the government would release 100 billion lira (£50.5m; $66m) of emergency funds. An investigation is under way to find the exact trigger for the explosion. Lebanon’s Supreme Defence Council said those responsible would face the “maximum punishment” possible. The ammonium nitrate that exploded came from a Russian-owned vessel that stopped in Beirut while it was sailing in November 2013 from Georgia to Mozambique.