Law enforcement officials in central Iowa have used ropes to drag three people from inside a 30-inch pipe - part of continued protests over construction of the Dakota Access oil pipeline.

The Des Moines Register says the three entered the pipe after 2 a.m. Thursday near the Des Moines River in Boone County. Sheriff's Detective Andy Godzicki says they managed to crawl 50 feet to 100 feet inside the pipe, taking food, sleeping bags and other supplies with them.

Workers banged on the pipe in a failed attempt to drive them out. Godzicki says they later refused requests to leave the pipe, so they were dragged out Thursday afternoon. Godzicki says they've been cited for trespassing and interfering with official acts.