Footage of the explosion posted on social media showed a column of smoke rising from the port, followed by an enormous blast, sending a white cloud and a fireball into the sky. Those filming the incident from high buildings 2 km (one mile) from the port were thrown backwards by the shock.
Heard 160 km away
The blast was heard throughout Cyprus, which is about 160 km away.
It revived memories of a 1975-90 civil war and its aftermath, when Lebanese endured heavy shelling, car bombings and Israeli air raids. Some residents thought an earthquake had struck.
Dazed, weeping and injured people walked through streets searching for relatives.
Rescuers worked through the night
Lebanese rescue workers dug through rubble looking for survivors of two powerful warehouse explosions as they wrecked buildings across the Lebanese capital.
Most powerful blast in years
Tuesday's blast at port warehouses storing highly explosive material was the most powerful in years in Beirut, already reeling from an economic crisis and a surge in coronavirus infections.
Hours after the blast, which went off shortly after 6 p.m. (1500 GMT), a fire blazed in the port district, casting an orange glow across the night sky as helicopters hovered and ambulance sirens sounded across the capital.
'Those responsible will pay'
President Michel Aoun said that 2,750 tonnes of ammonium nitrate, used in fertilisers and bombs, had been stored for six years at the port without safety measures, and he said that was "unacceptable".
Hariri tribunal verdict due
The explosion came three days before a U.N.-backed court is due to deliver a verdict in the trial of four suspects from the Shi'ite Muslim group Hezbollah over a 2005 bombing that killed former Prime Minister Rafik al-Hariri and 21 others.