(CNN) -- A lightning strike damaged runways at Bradley International Airport in Connecticut on Thursday as a line of thunderstorms snarled power lines and air traffic in the Northeast.
A bolt of lightning struck near the intersection of the two main runways around 3 p.m., according to John Wallace, director of communications for Bradley International Airport in Windsor Locks. The weather forced the airport into a holding pattern for a little under an hour as crews cleaned up debris and patched the runways' surface, he said. Both runways were open by Wednesday evening.
By 5 p.m., Connecticut Light & Power reported more than 33,000 customers without power. By 7 p.m. that number was down to 20,137. Crews were battling "a lot of tree damage and hundreds of lightning strikes," said Mitch Gross, spokesperson for Connecticut Light & Power. The power company was dealing with branches and trees falling and snapping utility poles, he said. All available crews were in the field assessing and repairing damage, he said.
Flights scheduled to leave from New England for other areas of the region were held as airports waited for severe weather to pass, but some flights were taking off to airports not affected by weather. As of 7 p.m., partial ground stops remained in effect at Boston Logan International Airport, all three major New York airports, all three Washington-area airports and other smaller airports in the region. Fights scheduled from Chicago's O'Hare International Airport and Hartsfield International in Atlanta that were bound for New England airports also were still delayed as of 7 p.m.
The storms were caused by a cold front stretching from Massachusetts through the Ohio Valley and into the Upper Midwest. Severe thunderstorm watches continued through the early evening across parts of New York, New Jersey, Delaware, Maryland, the District of Columbia, Pennsylvania, West Virginia, Virginia, Connecticut, Massachusetts, Rhode Island, Illinois, Minnesota, Iowa, Indiana and Wisconsin.
CNN's Monica O'Connor contributed to this report.