A man working on an oil rig in western North Dakota was crushed by a tank and killed. Thirty-one-year-old Karl Heller died when a tank that was being moved fell and crushed him. US federal safety authorities are investigating.

Counterweight Strikes and Kills Oilfield Worker

Worker A 35-year-old man was killed in a workplace accident at a Montana oil field. Kory A. Dawson was attempting to service a pumping unit when he was hit by the counterweight. The victim was taken by helicopter to hospital, where he was pronounced dead the same day. The field is operated by Great Plains Operating LLC, and Dawson was an employee of Green Oil Field Service.

One Dies, Four Hurt in California Refinery

One worker died and four were injured when a storage tank roof collapsed on them at an oil refinery. The recent accident at Conoco Phillips refinery occurred as the men installed plates on the floor of the empty 65-foot tank. The adjustable, 120-foot-diameter roof fell to just two feet above the tank floor. The workers were employed by HMT, a Texasbased contractor.

Officials identified the dead man as Mario Vasquez, 25, of San Pedro. Another man was in serious condition with head and back injuries, while three others suffered minor injuries.