A line of thunderstorms spawned by yesterday's heat and humidity rumbled across parts of Central Maryland yesterday, toppling trees and power lines in widely scattered areas and knocking out electrical service to about 9,000 homes.

Wind gusts reached 42 mph, and more than a half-inch of rain fell in parts of Carroll and Baltimore counties, the areas that appeared hardest hit by the storm.

The Baltimore Gas and Electric Co. said that the power outages were scattered across much of its system from 7 p.m. on and that work was under way to restore service to about 5,500 customers still without electricity late last night.

The storm provided only brief relief from the sizzling heat. The National Weather Service said temperatures today are likely to exceed 90 degrees -- for the eighth consecutive day -- and there is a chance of afternoon and evening thunderstorms.