If reports of a chemical weapons attack in a rebel stronghold in the eastern suburbs of Damascus, Syria, are true, it may have been the deadliest in decades.

The attack is believed to have come from chemical weapons on rockets that hit the neighborhoods of Ain Tarma, Zamalka and Jobar just before dawn. One nurse told Reuters that the death toll was 213, but reports from rebel groups put the number at over 750. Estimates appear to be rising.

David Kenner of Foreign Policy writes that if the higher estimates are true, it would not only be the worst chemical weapons attack in past two years of warfare in Syria, but also the worst globally since Saddam Hussein killed an estimated 5,000 people with poison gas in the Kurdish town of Halabja during 1988.

For now, we don't know what's going on exactly. Bashar al Assad's Syrian government is denying the reports, with state television saying that reports of an attack are being put out by rebels to distract a team of United Nations chemical weapons experts in the Syrian capital. However, as Kenner notes, it's unclear if the team will be able to get to the site of the alleged attack — despite being just 15 minutes away, their movements are reportedly heavily restricted.

Whatever happened, it's being extensively documented online. Reddit users are collecting videos of the aftermath, and they are truly horrifying to watch — some appearing to show dozens of bodies of children lying lifeless on the floor.

The videos below show some men, women and children who were reportedly recovering from the attack. WARNING: The footage may be extremely upsetting for some viewers:

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And another video allegedly showing children dying or recovering after the attack: