Three environmental activists were arrested in Texas on Monday after engaging in what organizers called an unprecedented action against the controversial Keystone XL oil pipeline, locking themselves inside a section of the pipeline itself. Two members of the Tar Sands Blockade chained themselves between barrels of concrete in a pipe segment waiting to be placed underground in East Texas along the pipeline’s southern leg. Construction was halted until the activists were removed and arrested after several hours inside. Their action comes one week after two other activists began a hunger strike following their arrest for protesting the pipeline. President Obama is set to decide on the Keystone XL in the coming months after delaying a move until after the 2012 elections.