TRENTON, N.J. — Powerful storms that thundered through eastern Pennsylvania, New Jersey and Connecticut downed trees and power lines, leaving nearly 400,000 customers without electricity and disrupting mass transit service in both states Wednesday.

In Pennsylvania, PECO says more than 165,000 homes and businesses were without power. Chester and Delaware counties were hardest hit, and officials said full service might not be restored until the weekend.

Forecasters are trying to determine whether straight line winds or a tornado caused most of the damage. The National Weather Service says a 71 mph wind gust was recorded at Philadelphia International Airport.

In one Philadelphia neighborhood, ferocious winds toppled five trees and caused a transformer to explode.

Fallen trees crushed cars at both ends of the 5300 block of Sylvester Street in the city’s Frankford section, blocking vehicle access. Three trees landed on homes.

Adrienne Johnson says the damage to her block resembled the aftermath of a tornado. She says the uprooted trees were old and needed to be removed long ago.

Johnson was home when the storm hit around 6 p.m. Tuesday. She says some people ran to their basements.

“You could hear the thunder and once the thunder hit, you heard the trees snap, cracking,” Johnson said. “It looks like a war-torn area. Trees are everywhere.”

The PATCO Speedline between southern New Jersey and Philadelphia was not operating during Wednesday’s rush because of power problems. Trains were expected to be running after midmorning. New Jersey Transit has suspended service on its Atlantic City rail line.

The Southeastern Pennsylvania Transportation Authority suspended service along some regional rail lines.