Witness: Blast sounded like a "jet breaking the sound barrier"

The Russian government is sending five planes of medical equipment and a team of doctors to set up a field hospital in Beirut to help the city in the aftermath of yesterday's explosion, the Russian Ministry of Emergency Situations said Wednesday, according to Russia's TASS news agency.

The ministry will also send a team trained for search and rescue operations and a mobile laboratory to identify cases of Covid-19.

Lebanon has recorded more than 5,000 cases of the virus, including 65 deaths, according to Johns Hopkins University.

Two Philippine nationals were killed in Tuesday's explosion in Beirut, the Philippine Embassy in Beirut confirmed Wednesday.

Eight other Philippine citizens suffered injuries, the Embassy said in a statement. One is in critical but stable condition.

Two of the injured were part of a group of 13 Filipino seafarers whose ship was docked “some 400 meters away from blast zone," the embassy said. The other 11 from that group are missing.

The embassy said it is working with local authorities to locate and ensure the safety of those who have not been accounted for.

A massive explosion rocked the Lebanese capital of Beirut on Tuesday evening, leaving dozens dead and thousands injured.

The blast has been linked to a large supply of confiscated and potentially unsecured explosive material, stored in a warehouse at the city's port, close to populated areas. As world leaders and international organizations step in to offer assistance, local officials are also launching an investigation into the blast.

As day breaks in Lebanon, authorities are scrambling to treat the wounded, search for survivors, and assess the full extent of the damage.

Here's what we know so far:

Leila Molana-Allen, a journalist with France 24 in Beirut, lives about a kilometer away from Beirut's port.

She said the explosion caused a blinding white light and "ripped" the doors and windows out of her apartment.

Watch her interview with CNN:

A warehouse storing thousands of tons of unsecured highly explosive material has emerged as a possible source of the massive blast that ripped through the Lebanese capital on Tuesday, killing at least 80 people, injuring 4,000 and sending a shock wave across the city that damaged buildings and blew out windows up to 10 kilometers (6 miles) away.

Lebanon's Prime Minister Hassan Diab said that 2,750 metric tons of ammonium nitrate, which is typically used as an agricultural fertilizer, had been stored for six years at a port warehouse without safety measures, "endangering the safety of citizens," according to a statement.

It's still not exactly clear what led to the ignition that wiped out entire streets across the seaside capital.

Initial reports in state media blamed the blast on a major fire at a firecrackers warehouse near the port, that likely spread to nearby buildings. However, the Prime Minister's account appeared to be backed by Lebanon's General Security chief Abbas Ibrahim, who said a "highly explosive material" had been confiscated years earlier and stored in the warehouse, just minutes' walk from Beirut's shopping and nightlife districts.

As Beirut's 4 million residents wake to the full horror and scale of the damage to their city, lives, and livelihoods, questions will be asked about why such large quantities of the dangerous chemical were allowed to be stored in the middle of the city without adequate safety measures, and who is responsible.

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An Indonesian national was "slightly injured" in Tuesday's explosion in the Port of Beirut, the country's Embassy in Lebanon said.

The embassy facility, which is located fewer than 10 kilometers (6 miles) from the port, was not damaged, said Basyiruddin Hidayat, an official with the Embassy of Indonesia in Beirut.

Hidayat said that according to the embassy's records, there are 1,447 Indonesian citizens in Lebanon, all of whom appear to be safe.

At least 80 people have died and more than 4,000 were wounded after the massive explosion in central Beirut on Tuesday, Lebanon's Health Minister Hamad Hassan said Wednesday morning. 

Hassan said four hospitals are out of service because of damage from the blast. 

He said the death toll will likely increase. 

Robert Baer, a former CIA operative with extensive experience in the Middle East, said videos of Tuesday's blast showed that while ammonium nitrate may have been present in the warehouse, he does not believe it was responsible for the massive explosion that ensued.

Initial reports blamed the blast on a major fire at a warehouse for firecrackers near the port, according to Lebanese state news agency NNA.

Lebanon's Prime Minister, Hassan Diab, later said that 2,750 metric tons of ammonium nitrate, a highly explosive material used in fertilizers and bombs, had been stored for six years at a port warehouse without safety measures, "endangering the safety of citizens," according to a statement.

Baer said he thinks that there were military munitions and propellants present. He speculated it could have been a weapons cache, but it's unclear who it belongs to.

"You look at that orange ball (of fire), and it's clearly, like I said, a military explosive."

Baer noted that white powder seen in the videos of the incident before the major blast are likely an indicator that ammonium nitrate was present and burning. He also noticed a lot of munitions going off ahead of the larger explosion.

No evidence of an attack: Baer said while he believes the explosion does not look like solely ammonium nitrate, there's still no evidence that this was an attack. The government has blamed poor management and vowed to get to the bottom of it.

Baer isn't confident we'll ever know the truth.

"I've worked in Lebanon for years, and no one is going to want to admit they kept military explosives at the port. It's a stupid thing to do."

Investigation launched: Prime Minister Diab's account appeared to be backed by Lebanon's General Security chief Abbas Ibrahim, who said a "highly explosive material" had been confiscated years earlier and stored in the warehouse, just minutes' walk from Beirut's shopping and nightlife districts.

The Prime Minister has launched an investigation into the explosion, saying he "will not rest until we find those responsible for what happened, hold them accountable, and impose maximum punishment."

As yet, there is no clear evidence to suggest the source of the blast.

Smoke rises in the aftermath of a massive explosion in Beirut, Lebanon, on Tuesday, August 4. Hassan Ammar/AP

Authorities are still investigating what exactly caused Tuesday's deadly explosion in Beirut, but public statements from key Lebanese officials have begun to focus on ammonium nitrate that was kept in a warehouse near the port.

Lebanon's Prime Minister Hassan Diab said in a statement that an estimated 2,750 metric tons of the substance had been stored there for the past six years. Lebanon's general security chief said the "highly explosive material" had been confiscated several years ago.

Ammonium nitrate, a compound of ammonia and nitrogen, is best known for being used in fertilizers and -- because it's incredibly volatile -- bombs.

The bombing of the Alfred P. Murrah Federal Building in Oklahoma City in 1995, which killed 169 people and injured 467, was carried out using two US tons of ammonium nitrate.

One of the worst accidents in US history involving a form of ammonia occurred in April 1947, when a ship loaded with ammonium nitrate caught fire while docked in Texas City.

The blaze caused an explosion and additional fires that killed almost 400 people and damaged more than 1,000 buildings, according to the website of the Texas Historical Association. The explosion was triggered by 2,300 US tons of ammonium nitrate, according to US Homeland Security.