Statements from officials in Turkey and Syria put the death toll at more than 500, after a huge 7.8 magnitude tremor struck near the Turkish-Syrian border.
An update from the Syrian health ministry says 237 people have been killed in the country – across the government-held provinces of Aleppo, Latakia, Hama and Tartus.
More than 600 people are injured, the ministry says.
The death toll in Turkey has risen to 284, with 2,323 people injured, Turkey’s Vice President Fuat Oktay says.
The numbers are expected to rise.
Some have said this may be Turkey’s largest earthquake on record – as strong as one that happened over 80 years ago.