pipeline2Some opponents of the oil pipeline being built across Iowa are going to extreme measures to slow up construction.

Three protesters who oppose the Dakota Access oil pipeline crawled into a pipe at a construction site in central Iowa’s Boone County on Thursday and refused to come out.

They were so far back into the pipe, pipeline construction workers sent in oxygen, worried the demonstrators’ lives were at risk.

The Boone County sheriff decided not to send in deputies to get them, fearing for their safety.

The protesters eventually came out on their own after about 12 hours — and faced tresspassing charges.