BELLINGHAM, Wash. (AP) — Crews on Tuesday removed the train cars carrying crude oil that derailed north of Bellingham and near the Canadian border last week.

BNSF employees and contractors loaded the cars onto flatbed trucks for removal from the derailment site in Custer. BNSF spokeswoman Courtney Wallace said all the cars would be removed on Tuesday. She also confirmed Tuesday that ten cars of the tanker train hauling oil derailed on Dec. 22, which was several more than previously reported.

Five cars caught fire, sending a large plume of black smoke into the sky and prompting evacuations. Three cars were punctured and leaked oil.

The cause of the derailment remains under investigation by the FBI and Wallace said she had no new information about the investigation on Tuesday. The derailment happened when the train was moving at about 7 mph, making it a low-speed derailment, she said.

Officials with the Department of Ecology also remain at the site with soil testing and remediation work to start this week, she said. On Sunday, Ecology officials said on Twitter that crews were continuing to remove oil from the site.

ed, spilling an unknown amount of crude oil onto the ground.