At least one US citizen was among those killed in the devastating Beirut explosion Tuesday night, and several others were injured. The death toll so far stands at 135, with another 100 still missing and search and rescue efforts continuing, ABC News reports. Another 5,000 were wounded, and as many as 300,000 were left homeless when the explosion flattened parts of the Lebanon capital. The cause remains unknown, but more than 2,700 tons of ammonium nitrate that was being stored in a warehouse at the port appears to be to blame; some of the managers of the warehouse, which officials say was unsafe, are being held under house arrest as authorities investigate. US Defense Secretary Mark Esper said Wednesday that based on information coming in, "most believe it was an accident, as reported." But CNN notes that at a briefing later Wednesday, President Trump repeated unsubstantiated claims that "perhaps it was an attack."
CNN also has an explainer on how the highly explosive agricultural fertilizer apparently got from a Russian cargo ship to the warehouse, where it ended up remaining for years. The ship made an unplanned stop in Beirut in 2013 and was then abandoned and ultimately confiscated by Lebanese authorities. Though officials warned that the ammonium nitrate was dangerous, it was unloaded into the port the following year and never disposed of—despite the fact that the warnings continued. "This is a catastrophic regulatory failure because regulations on the storage of ammonium nitrate are typically very clear," an expert says. "The idea that such a quantity would have been left unattended for six years beggars belief and was an accident waiting to happen." Newly released video of a bridal photo shoot shows the moment the blast rips through an otherwise peaceful moment. (Read more Beirut stories.)