The Sundhnukur row of craters on Iceland’s Reykjanes Peninsula erupted this week, forcing road closures and evacuations, including of the Blue Lagoon geothermal spa.

The eruption, which started Wednesday, is the fifth and most powerful to take place since a volcanic system near the town of Grindavik resumed activity in December for the first time in 800 years, according to The Associated Press.

The eruption started at 12:46 p.m., with lava flowing westward toward the road to Grindavik, the Icelandic Meteorological Office said. The volcanic fissure spewing lava grew to a length of over 2.1 miles.

Around 200 to 300 people were in Grindavik at the time of the eruption. They were safely evacuated.

“There was an alarm; the officer told everyone to get out. Everyone stopped working, ran out and into their cars. I’m not even wearing shoes. I’m just wearing my work clothes and my hairnet. Everyone just went out fast. My heart skipped a beat,” Pattra Thipnet, who works at a fish processing plant in Grindavik, told Icelandic national broadcaster RUV.

The evacuation, Ms. Thipnet added, took less than five minutes.

Grindavik was first evacuated in November, ahead of the first eruption the next month. Wednesday’s activity buried two of three roads in and out of the town of 3,800 in lava, according to AP.

The Blue Lagoon spa had 700 to 800 people.

“We were going to go to the Blue Lagoon and enjoy the day there, but the police had to close the road and told us that there could be an eruption,” Swedish tourist Johannes Aasa told RUV.

The Blue Lagoon remains closed through Friday, the spa posted on its website.

No new explosive activity occurred Thursday, the Icelandic Meteorological Office said.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.