A volcano has erupted on the Reykjanes peninsula of south-west Iceland after weeks of intense earthquake activity.
About 4,000 people were evacuated from the fishing town of Grindavik earlier this month, and the nearby Blue Lagoon geothermal spa was closed.
The eruption started north of the town at 22:17 local time (22:17 GMT), the Icelandic Met Office said.
It is not expected to bring the same level of disruption as one in 2010, which halted European air travel.
The region around the capital Reykjavik has been experiencing an increase in earthquake activity since late October.
The Met Office said that the eruption was located about 4km (2.5 miles) north-east of Grindavik and the seismic activity was moving towards the town.
Images and videos posted on social media showed lava bursting from the volcano just an hour after an earthquake swarm, a series of seismic events, was detected.
The eruption can be seen from Reykjavik, which is about 42km north-east of Grindavik.
One eyewitness there told the BBC that half of the sky in the direction of the town was “lit up in red” from the eruption, and smoke could be seen billowing into the air.
Police have warned people to stay away from the area.
The length of the crack in the volcano is about 3.5km, with the lava flowing at a rate of around 100 to 200 cubic metres per second, the Met Office said.
It added that this was many times more than in previous eruptions on the Reykjanes peninsula in recent years.
A senior police officer at the Civil Defence told national broadcaster RUV that the eruption had happened quickly and appeared to be “quite a large event”.
