Icelandic officials are describing the country's latest volcanic eruption - threatening the fishing town of Grindavik - as the "worst case scenario".
Despite months of preparations, including mandatory evacuations, lava seems to spewing from inside barriers.
Authorities are now trying to divert it, and cool it - though some homes have already caught fire.
Sky's science correspondent Thomas Moore is in the nearby town of Keflavik:
"This isn't about people's lives. They're all safe. They've been evacuated. It's not really just about their homes either. This is a whole community that has been built up over many generations. Now that is at risk".