A huge explosion has rocked the Lebanese capital of Beirut, killing at least 70 people and injuring more than 3,000.
Videos posted on social media captured the massive blast on Tuesday near the city’s harbour, showing a mushroom cloud of dust billowing into the air.
It was reportedly caused by "highly explosive sodium nitrate" confiscated from a ship by Lebanese authorities placed in one of the warehouses located in the port.
Officials said at least 70 people had been confirmed dead and more than 3,000 were hurt.
Prime Minister Boris Johnson confirmed that British nationals were among those caught up in the aftermath of the blast.
Mr Johnson said the Government is “ready to provide support in any way we can”, while Foreign Secretary Dominic Raab said the UK stands in solidarity with Lebanon.
In a tweet, Mr Johnson said: “The pictures and videos from Beirut tonight are shocking. All of my thoughts and prayers are with those caught up in this terrible incident.
“The UK is ready to provide support in any way we can, including to those British nationals affected.”
Officials expected the death toll to rise sharply as emergency workers dug through rubble across a swathe of the city to rescue people and remove the dead.
It was the most powerful blast to hit Beirut in years, making the ground tremble.
"What we are witnessing is a huge catastrophe," the head of Lebanon's Red Cross George Kettani told broadcaster Mayadeen.
"There are victims and casualties everywhere - in all the streets and areas near and far from the explosion."
The Prime Minister's wife and daughter were injured in the blast, according to local news media.
The country's Health Minister Hamad Hasan was quoted by Lebanese LBC television as saying the explosion had caused a "very high number of injuries" and extensive damage.
Al Mayadeen television said hundreds were wounded. Some local TV stations reported the blast was at Beirut's port inside an area where fireworks were stored.
The force of the first explosion set the port alight. It was then followed by an even larger second explosion that shattered windows miles away and tossed cars onto their roofs.
A witness told Reuters: "I saw a fireball and smoke billowing over Beirut. People were screaming and running, bleeding.
"Balconies were blown off buildings. Glass in high-rise buildings shattered and fell to the street."
One Twitter user wrote: "My brother sent me this, we live 10 KM away from the explosion site and the glass of our buildings got shattered."
Reports of the blast being felt as far away as Cyprus were reported on social media.
Other footage showed cars flipped onto their roofs and streets carpeted in ash.
There were initial reports that a fire had broken out a fireworks storehouse before the explosion at the port, although the cause of the blast is unconfirmed.
A reporter for The Daily Star, a Lebanese newspaper, said the newspaper’s offices had been damaged by the blast.
Posting on Twitter, the reporter, Ghana Alsharif, wrote: “Massive explosion in Beirut. Footage from the daily star office now in Lebanon.”
— Abir Ghattas (@AbirGhattas)
Leila Molana-Allen, a Middle East correspondent for channel France24 English who is based in Beirut, posted on social media to say that her apartment in the city had been blown apart at around 4.15pm GMT.
The reporter wrote: “My apartment in Beirut was just blown apart. We think it was a missile from a jet. We're ok.”
Foreign Secretary Dominic Raab offered support to British nationals affected by the explosion.
"My thoughts and prayers are with those affected by the devastating explosion in #Beirut today", he tweeted.
"The UK stands in solidarity with the people of Lebanon 🇱🇧 and is ready to offer help and support including to those British nationals impacted."
The blast came as the country awaits a verdict in a trial for the killing of ex-PM Rafik Hariri in 2005.
This page is being updated.