At least nine people, including a state trooper who was responding to a crash, have been killed amid a winter storm that has battered the Midwest and continues to dump several inches of snow in the Washington, D.C., metro area.

The storm that began in parts of the Midwest on Friday snarled traffic on highways with a deadly mix of sleet and slush, left thousands without power and canceled dozens of flights. It has left dozens of casualties in its trail as it moved eastward, dropping six to seven inches of snow in parts of Maryland and Virginia.

Missouri took the brunt of the damage, logging more than 800 snow-related crashes that injured 57 and killed four, according to the Missouri State Highway Patrol. Among those killed were a 53-year-old woman and a 14-year-old relative. Authorities say the woman lost control while driving on a snow-covered road in rural Missouri on Friday and drifted into the path of an oncoming vehicle.

In a suburb of Chicago, Illinois State Police Trooper Christopher Lambert was standing outside his patrol car Saturday at the scene of a three-car crash when a vehicle struck him, authorities say. Lambert, a five-year veteran of the state police who previously served in the Army, died later at a hospital. The state police said earlier Saturday that they had responded to more than 200 snow-related crashes, including one other fatality.

Three storm-related deaths have been reported in Kansas, including a crash involving a 62-year-old man on the Kansas Turnpike.