On Wednesday Tianjin was the site of a massive explosion. Here's what you need to know about the city

On Wednesday night, two huge explosions rocked the northern Chinese port city of Tianjin. At least 50 people died, including 17 fire-fighters. Another 700 more were injured, dozens of them critically.

Exactly what caused the explosion is still unclear. They took place in a warehouse owned by a company called Ruihai Logistics, which specialises in handling compressed gas, flammable liquids, and other “hazardous goods”. Whatever it was that ignited, it sparked a fireball visible from space and a shockwave that damaged buildings as far as 2km away.

This grainy image of the fire in progress was posted to Chinese social network Weibo.

Very little news from Tianjin makes it into the western press – which is odd, in its way, as it’s huge, one of that vast number of Chinese cities that are bigger than most European capitals, yet almost unknown in the west.

Tianjin’s population is around 11m, on a par with that of London or Paris; depending on how you count, it’s the fourth or fifth largest city in China, with a population of 11m. During the Boxer Rebellion of 1899-1901, it was briefly the seat of the government; today it’s mostly the main port for Beijing, which lies 170km north east up the Hai River.

One of the President Xi Jingping’s biggest economic plans is to link the two cities, as well as the Hebei province that surrounds them, into a single “megalopolis”. This will not be one big city, but an urban zone, like the north eastern seaboard of the United States or Europe’s “blue banana”.

Ultimately, the Jing-Jin-Ji region, as it’s known, will have a population of around 130m. This, the government hopes, will help the regions’ economy catch up with the richer Shanghai and Pearl Delta (Hong Kong, Guangzhou, Shenzhen) regions. You can already see that the region is pretty urbanised by looking at the map:

At time of writing, the local emergency services were in the process of removing dangerous chemicals from the blast zone. Investigation into the causes of the disaster is continuing.

Here are some more pictures of the explosion and its aftermath.