Cleanup of an oil spill caused by the derailment of nearly three dozen oil tankers in northwestern Iowa has begun. Lyon County Sheriff Steward Vander Stoep says between 30 and 40 semitrailers containing cleanup equipment had arrived at the scene near Doon, Iowa, this (Friday) afternoon.

Tank cars carrying crude oil are shown derailed about a mile south of Doon, Iowa, Friday, June 22, 2018. (Tim Hynds/Sioux City Journal via AP)

BNSF spokesman Andy Williams says 33 oil tanker cars hauling crude oil from Alberta, Canada, derailed around 4:30 a.m. Friday just south of Doon. Williams says some of the tankers were compromised, causing the oil to leak into floodwaters and eventually into the rain-swollen Little Rock River, but officials don’t yet have an exact number of tankers that leaked oil.

Williams says clean-up crews are working to contain the oil as close to the derailment as possible using containment booms, skimmers and vacuum trucks. City public information officer Travis Olson says the wells were shut down as soon as Rock Valley officials were told of the derailment and oil spill north of them early Friday morning.

Olson says Rock Valley’s water towers also will be drained as a precaution. In the meantime, the city is getting its water from the nearby Rock Valley Rural Water system, which Olson says is not in danger of being contaminated by the spill. Olson says the city will use the rural water supply until testing by the Iowa Department of Natural Resources confirms the safety of the city’s drinking water. He did not know when that testing would be finalized.