No cause confirmed, although there's tons of rampant speculation. It looks like whatever caused it involved a fire beforehand. The one just following the 30 second mark looks like a weapons depot explosion.

Reminds me a little of this one from China

And this one from Ukraine

And this one in the US

It looks VERY similar to this Russian ammunition depot explosion.

Some more angles of the Beirut explosion. It's clear there was a fire beforehand.

very scary, I hope everyone is ok

Reminds me off Enschede fireworks depot fire

Although that visible shock wave in Beirut suggests a lot more powerful stuff exploding.

"Lebanon's internal security chief Abbas Ibrahim said the explosions took place in a section of the port housing highly-explosive materials."

https://www.arabnews.com/node/1714671/middle-east

I was reading the live ticker on the guardian, truly horrific what happened. Has news updates and pictures:

https://www.theguardian.com/world/live/2020/aug/04/beirut-explosion-huge-blast-port-lebanon-capital

Apparently a whooping 2750 tons of Ammonium Nitrate (for fertilizer production) exploded there in that fire at the harbor. A Monsanto harbor (who probably owned that material that exploded) next to it was totally demolished by the explosion.

Yeah, several warnings were issued, though the current tests don't show any toxins yet.

And with most windows shattered by the shockwave, it would be pretty much impossible for most people to hide from it inside.

If it was Monsanto's Ammonium Nitrate, then they might have to pay for the dommages done, the Prime Minister of Lebanon already told reporters that the owners will have to pay. That might just be enough to break it's neck.

Following.
Definitely interested to see what the catalyst was.

There was clearly a fire before hand that was affecting various electrical components. - That coloured smoke usually implies pesticides/fertilizers.

This is a disgusting and despicable post.