In a statement, Texas-based Dakota Access said "it's a shameful act by a group of people trying to disrupt our energy security and independence."

DES MOINES, Iowa (AP) — Machinery located at three oil pipeline construction sites in central Iowa was found extensively damaged by fire Monday in what the company building the pipeline called a shameful act.

There's little doubt the fires were intentionally set along the Dakota Access pipeline, said Jasper County Sheriff John Halferty. Damage to a bulldozer and other large tracked equipment was estimated at $1 million, he said.

The sheriff's office was alerted around 6 a.m. Monday to a fire in a farm field 4 ½ miles west of Newton. Later, deputies learned of a second pipeline equipment blaze about 2 ½ miles southeast of Reasnor and a third site where four machines were damaged north of Oskaloosa, the Newton Daily News (http://bit.ly/2apGmwK ) reported.

In a statement, Texas-based Dakota Access said "it's a shameful act by a group of people trying to disrupt our energy security and independence."

"We have increased security along the route and are actively pursuing the situation with law enforcement. If caught, we will prosecute to the maximum extent allowed by law, both criminally and civilly," spokeswoman Lisa Dillinger said in a statement. "We will not tolerate this kind of activity."

Environmental, American Indian and landowner rights groups have vigorously fought approval of the pipeline and have vowed to continue protests and acts of civil disobedience.

"I've made lots of statements on this pipeline over the last two years and I've encouraged people to get ready for any nonviolent action possible but torching construction equipment was not on the list," said Ed Fallon, director of Bold Iowa, a group that promotes renewable energy and fights fossil-fuel expansion projects.

Dakota Access, a subsidiary of Dallas-based Energy Transfer Partners, plans construction of a $3.8 billion, 1,168-mile project that cuts through Illinois, North Dakota and South Dakota. It also crosses 18 Iowa counties diagonally from northwest to southeast.

Today's top stories

Reconstruction of Frank J. Wood Bridge in Maine Under Way

Buffalo Looks to Improve, Protect Ralph Wilson Park

Webuild Ready to Rebuild Collapsed Baltimore Bridge

Make Eliminating Jobsite Distractions Company Safety Goal

VIDEO: Komatsu Holds Demo Days at Cartersville Customer Center

Hansen Hosts 59th Annual Spring Nitke Contractor Auction

RMS Rentals Welcomes Guests to Open House in Savage, Minnesota

Mixed-Use Project in SW Philadelphia's Africatown to Soon Begin Construction