A volcano in south-west Iceland erupted on Friday, following thousands of smaller earthquakes in the area in recent weeks.
The eruption occurred near Fagradalsfjall, a mountain on the Reykjanes Peninsula, around 30 kilometres south-west of the capital Reykjavík.
Pictures on local media showed a bright-red night sky. A picture posted on Twitter by the Icelandic Meteorological Office showed smoke rising from glowing lava streams.
"I can see the glowing red sky from my window," said Rannveig Gudmundsdottir, a resident of the town of Grindavik, only 8km from the eruption.
"Everyone here is getting into their cars to drive up there," she said.
The eruption posed no immediate danger to people in Grindavik or to critical infrastructure, the IMO said.
"I think we couldn't hope for anything better than that," IMO volcanic hazards co-ordinator Sara Barsotti said.
Iceland's Department of Emergency Management said it was not anticipating evacuations because the volcano is in a remote valley, about 2.5km from the nearest road.
Police ordered residents living east of the volcano to close their windows and stay indoors due to the risk from volcanic gases carried by the wind, especially sulphur dioxide.
Reykjavik's international Keflavik airport was not closed following the eruption, but each airline had to decide if it wanted to fly or not, IMO said.
Unlike the Eyjafjallajokull volcano eruption in 2010, which halted approximately 900,000 flights and forced hundreds of Icelanders from their homes, this eruption is not expected to spew much ash or smoke into the atmosphere, the IMO said.
The Krysuvik volcanic system is located south of Fagradalsfjall on the Reykjanes peninsula.
Eruptions in the region are known as effusive eruptions, where lava flows steadily out of the ground, as opposed to explosive ones which spew ash clouds high into the sky.
The region has been under increased surveillance for several weeks after a 5.7-magnitude earthquake was registered on February 24 near Mount Keilir on the outskirts of Reykjavik.
That quake was followed by an unusual number of smaller tremors – more than 50,000, the highest number since digital recordings began in 1991.
The seismic activity moved several kilometres south-west since the quake, concentrating around Fagradalsfjall, but had slowed in the past few days.
Iceland is located on top of the Eurasian and the North American tectonic plates, making it a seismic and volcanic hotspot as the two plates move in opposite directions.
Iceland has 32 volcanic systems currently considered active, the highest number in Europe. The country has had an eruption every five years on average.
The Fagradals volcano had been dormant for 6,000 years, and the Reykjanes Peninsula had not seen an eruption in 781 years.