Crews are cleaning up after an estimated 50 to 200 tons of oil leaked into the St. Lawrence river south of Montreal last night. The Canada Steamship Lines vessel ran aground near the Côte Sainte-Catherine lock after losing power. The fuel tank was punctured. The lock has now been closed to contain the spill, blocking some river traffic. The area affected is about 500 metres by 500 metres. Residents living close by have been cautioned to check their water for signs of contamination.