'The apartment shook horizontally,' says Beirut resident

Smoke rises in Beirut. Mohamed Azakir/Reuters

A red cloud hung over Beirut in the wake of the blast, as firefighting teams rushed to the scene to try to put out the fire.

Homes up to 10 kilometers (6 miles) away were damaged, according to witnesses, and footage from local media showed wrecked cars, apparently flipped over by the force of the blast.

One Beirut resident who was several kilometers away from the site of the explosion said her windows had been shattered by the explosion. "What I felt was that it was an earthquake," Rania Masri told CNN.

The huge explosion in Lebanon's capital, Beirut, blew out the windows of the CNN bureau, according to CNN's correspondent Ben Wedeman, who said he saw a cloud of red smoke drift over the city after the blast.

Wedeman said he had "never felt anything like it ... [I've] been around the block and seen pretty large explosions ... and this was bigger," he told CNN's Becky Anderson, adding that he only heard and felt one explosion.

"As far as I can tell there was just one absolutely massive explosion which caused all this damage in the Lebanese capital."

Lebanon's state-run NNA news reports that a major fire broke out in a warehouse used for storing firecrackers, near Beirut's port, and strong explosions were heard shortly afterwards.

Wedeman said the cause of the blast was "still not clear -- if it was fireworks, as some news sources are saying -- they are some damn big fireworks."

An explosion is seen in Beirut, Lebanon, on August 4. Anwar Amro/AFP/Getty Images

A large explosion rocked the Lebanese capital Beirut on Tuesday, damaging buildings and offices around the city. 

Lebanon's state-run NNA news reports that a major fire broke out in a warehouse used for storing firecrackers, near Beirut's port, and strong explosions were heard shortly afterwards.

Firefighting teams have rushed to the scene and are working to put out the fire.