An apparent tornado knocked down power lines and tree limbs Saturday afternoon in the Essex and Rockaway Beach sections of Baltimore County, authorities said. A tree landed on a house in the 900 block of Lance Avenue, fire officials said. The family was displaced, but no one was injured. Police began receiving reports of storm damage about 4 p.m., including tree branches blocking roads. More than three dozen houses sustained minor damage, said Baltimore County Fire Department spokeswoman Elise Armacost. The National Weather Service made a preliminary assessment that the storm was a tornado with peak winds of 90 miles per hour, said forecaster Bryan Jackson of the weather service's office in Sterling, Va. He said the storm touched down at 3:44 on Lance Avenue and cut a narrow 5-mile path to Island View Road, snapping and uprooting dozens of trees before dissipating by about 3:54.