Workers tend to the scene of a train derailment in Watertown, Wis. Monday, Nov. 9, 2015, after a 13 cars of a Canadian Pacific train carrying crude oil overturned Sunday. One of the cars was punctured, spilling less than 1,000 gallons of oil. Thirteen of 110 cars derailed in Watertown Sunday afternoon, the second derailment in Wisconsin in as many days. (AP Photo/John Hart, Wisconsin State Journal)

WATERTOWN, Wis. - Contractors worked to clear more than a dozen derailed cars of a loaded Canadian Pacific Railway train Monday after thousands of litres of crude oil spilled from one tanker, causing the evacuation of a neighbourhood in a small southern Wisconsin city.

Residents who evacuated dozens of homes in Watertown following the derailment Sunday afternoon were still being kept away Monday as 12 derailed cars were moved to a temporary track. Thirteen of the train's 110 cars derailed, and 109 of them were carrying crude oil, officials said.

Crews were dismantling and removing one car that was punctured, and it spilled no more than 3,800 litres, Canadian Pacific (TSX:CP) spokesman Andrew Cummings said. The railroad said the leaking car was sealed, the oil contained and siphoned off, and that none of the product reached any waterways.

It was the second freight train derailment in as many days in Wisconsin. On Saturday, 25 BNSF train cars including tankers derailed, spilling more than 68,000 litres of ethanol along the shores on the Mississippi River in western Wisconsin.

BNSF said railroad crews stopped the leaks from five tanker cars and placed containment booms along the shoreline. No one was hurt. BNSF said it expects the tracks to return to service Monday.

Federal Railroad Administration regional administrator Steven Illich said there was no reason to believe the Watertown derailment was anything but an accident.

"We have no indications that it is criminal. However, again, we won't rule anything out until we have a chance to do a full investigation," Illich said. Investigators will look at several key areas including the track, he added.

"There will be metallurgic tests that will be done, not only on the rails, but on the wheels on the train cars," Illich said.

Watertown fire chief Gregory Michalek said Monday that residents who evacuated 35 homes following the spill cannot return home until the cleanup is complete. They were escorted to their homes by officials late Sunday to retrieve pets, medicine and clothes. Officials will re-evaluate the situation in Watertown on Monday evening and decide if residents can return, Michalek said.

CP said in its statement that it had reserved hotel rooms for all affected families.

News from © The Associated Press, 2015