Lebanon imposes state of emergency after massive explosion killed at least 135 people and wounded 4,000

A Catholic church in Beirut was televising its Tuesday mass as part of its Covid-19 safety protocols, but it was interrupted when the massive explosion went off.

Video of the service shows parts of the ceiling falling as a priest ran for cover, getting injured in the process.

Pope Francis has called on people to pray for Lebanon in the aftermath of Tuesday’s deadly explosion.

Watch the moment here from Al Hurra TV:

The death toll for Tuesday’s blast increased to 135, Lebanon’s Health Minister Hamad Hassan told Al-Manar television.

Another 5,000 people are wounded and dozens more are still missing, he said. 

The office of the Paris prosecutor said in a statement on Wednesday that 21 French nationals were injured in the blast in Beirut.

This has prompted the Prosecutor's Office to open an "investigation for unintentional injury," the statement says, a standard procedure when French nationals are injured abroad, a source close to the investigation told CNN. 

French President Emmanuel Macron will visit Beirut on Thursday to show “solidarity” with the Lebanese people in the aftermath of Tuesday’s disastrous explosion, according to the Twitter account of the Lebanese presidency.

Ghassan Hasrouty worked in the port in Beirut where the massive explosion took place. He went to work Tuesday morning, and that’s the last time his family saw him. Now, his daughter Tatiana Hasrouty said she is considering the possibility that he’s trapped under rubble.

Hasrouty expressed her frustration with the government’s response to the disaster, saying the authorities are not searching the blast site.

“No authority is searching for them where they are,” Hasrouty says. “They say they don't have the capabilities, they don't have machines or construction machines to remove the rocks to find them. But we know for him and other workers of his, they are stuck there.”

“We don't really know what to do,” she added. "It's really frustrating and devastating.”

She said no authority has contacted the family.

Watch Tatiana's plea:

CNN's senior international correspondent Ben Wedeman went inside a home overlooking the port where Tuesday’s massive explosion took place in Beirut. The home was inhabited by an elderly couple.

Looking out through the walls of the home that have collapsed, Wedeman describes the state of the warehouse that exploded. What was simply dry ground before, Wedeman says, is now a crater, with water flowing into the area.

The Lebanese government has committed to conducting a transparent investigation into the explosion, but Wedeman says it is “scant consolation” to the families of those killed, injured and missing.

Beirut's governor said in an interview earlier today that at least 300,000 people have been displaced from their homes by the blast.

Go inside the home damaged by the explosion:

An aerial view of Beirut. AFP/Getty Images

Lebanese authorities declared Beirut a “disaster city" on Wednesday, according to Lebanon State-run NNA news, citing a statement released by the country’s Minister of Information Manal Abdel Samad Najd.

A state of emergency has been declared in Beirut for two weeks, Najd said in the statement, adding this could be extended.

The country’s Council of Ministers made the two decisions on Wednesday in an “extraordinary session” headed by President Michel Aoun and in the presence of the prime minister.

It was also decided in the extraordinary session "to instruct the High Relief Commission to secure shelter for families whose homes are no longer fit for housing, open schools and hotels to receive citizens, and request from the security services to ensure Not to tamper with the crime scene," the statement said.

A nurse in Beirut takes care of three babies in a damaged hospital on August 4. Bilal Jawich/Xinhua/Getty Images

A nurse pulled three babies out of a hospital rocked by the massive explosion in Beirut on Tuesday, a photographer who took her picture told CNN Arabic.

Photojournalist Bilal Jawich said he was at home on the outskirts of Beirut when the blast, which has left at least 100 dead and thousands injured, rocked the Lebanese capital.

"I followed the smoke until I reached the port of Beirut," he said, explaining that "professional intuition" took him to Al Roum hospital, in the Ashrafieh district. The area has been left devastated by the blast.

"However, the nurse looked like she possessed a hidden force that gave her self-control and the ability to save those children," Jawich said. "People stand out amidst these violent and dark and evil circumstances and this nurse was up to the task."

Jawich said the nurse told him later that evening that she was in the maternity ward when the blast hit. She said she had been knocked unconscious, and when she came around “found herself carrying these three children,” he told CNN Arabic.

Not everyone in the hospital was so lucky. George Saad, emergency preparedness and disaster manager for the hospital told CNN that some 12 patients, two visitors and four nurses died in yesterday's incident, while two remain in critical condition. Some 80% of the hospital had been damaged, along with 50% of its equipment, he said.

WATCH:

Drone footage captured by CNN this morning showed the destruction left in the wake of Tuesday’s deadly explosion in Beirut.

At least 100 people were killed in the blast, and the death toll could rise as many more people are reported missing. At least 4,000 people were injured in the explosion.

Watch the footage:

A helicopter fights a fire at the scene of an explosion on August 4. STR/AFP/Getty Images

We're still not exactly sure what caused the deadly explosion in Beirut yesterday, but Lebanon's prime minister said an investigation would focus on an estimated 2,750 metric tons of the explosive ammonium nitrate stored at a warehouse.

So what is ammonium nitrate? Also known as AN, it's a compound of ammonia and nitrogen, is a highly volatile material used in agricultural fertilizers and bombs.

Disasters involving AN are rare, considering the US uses millions of tons of it every year in fertilizers, according to the Environmental Protection Agency. "Pure" solid AN is quite stable, but if the compound is mixed with any contaminants, even in small traces, the mixture becomes much more prone to detonation  — which is why there are normally stringent government guidelines for how to treat and store it properly.

For instance, AN shouldn't be stored with any fuel, organic materials, chlorides or metals, said the guide — all potential contaminants. The EPA guidelines also recommend fire resistant walls in the storage unit, noncombustible flooring, and — crucially — controlled temperatures.

AN doesn't burn, but if exposed to heat, it can melt — which releases combustible toxic gases that can cause an explosion. It's even more dangerous if there is a large supply of AN all stored together, because once a small section of AN begins to melt and explode, the resulting heat can set off the rest of the supply.

Some history: One of the worst disasters 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 fire caused an explosion and additional fires that damaged more than 1,000 buildings and killed nearly 400 people, according to the website of the Texas Historical Association.

For perspective, that explosion was triggered by 2,300 US tons (about 2087 metric tons) of ammonium nitrate, according to US Homeland Security.

And the 1995 Oklahoma City Bombing, a US domestic terror attack that killed 169 people and injured 467, used only two US tons (1.8 metric tons) of ammonium nitrate.