6.1-magnitude earthquake strikes Costa Rica

From CNN: Strong Costa Rica quake kills two girls

• The girls died after the landslide destroyed their home, officials say
  
• More than 1,000 tourists were stranded near Vara Blanca, media reports say
  
• Costa Rican seismologists say tremor's epicenter near Poas Volcano
  
• Seismologists say more than 600 aftershocks have already struck

The Volcanological and Seismological Observatory of Costa Rica told CNN that the tremor's epicenter was 10 kilometers east of the Poas Volcano, Costa Rica's most-visited national park.
"I have been sitting here watching my monitors and we have had more than 600 aftershocks in the past three hours," said Victor Gonzalez, a seismologist with the observatory.