A pharmacy student in Belfast who grew up in Beirut and a Northern Irish explosives expert have spoken of their shock at the devastating blast in the Lebanese capital.
The explosion on Tuesday killed at least 135 people and injured more than 5,000 - with another 100 people still missing.
Lebanese President Michel Aoun said 2,750 tonnes of unsafely stored ammonium nitrate was to blame for the blast.
Zina Alfahl (29) grew up in Beirut and moved to Belfast in 2018 to study for a PhD at Queen's University.
She said friends at home were worried about their future.
"A lot of them will live in the mountains or other cities, but this will affect everyone in the country," Ms Alfahl added.
"It's heartbreaking. I was shocked. You can't imagine something like this happening in a beautiful city like Beirut."
Ms Alfahl was in Beirut in 2005 when then prime minister Rafik Hariri was killed by a massive car bomb near the scene of Tuesday's explosion.
Tensions had been high in the city this week ahead of a verdict on his death due on Friday.
"Our house was in the area at the time (of the bomb) and my grandmother said it felt like an earthquake," Ms Alfahl said.
"I've asked many people and they've said what happened then was only 10% of the explosion on Tuesday.
"You can't imagine the damage. In just a couple of seconds, people lost everything.
"There are many people who are missing. I'm seeing a lot of pages where they're putting up pictures, but people are recognising that they're dead."
Lebanese hospitals were already struggling to cope with coronavirus before Tuesday's massive explosion.
"Another problem is that many people are starving and can't take their money out of the banks. That was already happening," Ms Alfahl said.
"I'm not sure, but from what I've seen before, I don't think the government can support them.
"They need outside help now. Without it they cannot survive a huge explosion costing millions of dollars."
Philip Ingram, a former military intelligence officer and explosives expert from Northern Ireland, said he believed the blast was "a tragic accident with a series of circumstances that have come together to cause a massive explosion".
"The trouble is that a lot of countries in the Middle East are not well known for applying regulations (on dangerous substances)," he added.
"The facility in Beirut is unlikely to be a specialist one, which in itself can lead to very dangerous circumstances.
"The crazy thing is, this was an official facility. The government had seized these goods from a ship. Over time it became a disaster waiting to happen.
"To say the government is weak and unstable is an understatement. It has real difficulty managing what's going on in the country and this will probably not have even been on its radar."
The international community promised to send Lebanon aid as it struggles to recover.
French president Emmanuel Macron is due to visit the country, a former protectorate of France, today. His government has already dispatched two planes full of specialists, rescue workers and supplies to Beirut.
The European Union has activated its civil protection system to round up emergency workers and equipment.
The EU commission said the plan was to send more than 100 firefighters with vehicles, sniffer dogs and specialist equipment to Lebanon. The Czech Republic, Germany, Greece, Poland and the Netherlands have signed up to the relief effort, with other nations expected to follow suit.
The EU's satellite mapping system will also be used to help the local authorities establish the extent of damage.
Cyprus, where Tuesday's blast was felt, is sending in emergency personnel and sniffer dogs.
Help is also coming from closer to home. Iraq is sending six trucks of medical supplies and an emergency medical team and Egypt and Jordan are supplying field hospitals.
Israeli prime minister said his country was ready to help the Lebanese even though the two nations are technically at war.
The World Health Organisation is sending medical supplies to cover up to 1,000 trauma interventions and up to 1,000 surgical interventions following a request from local health chiefs.