An apparent electrical fire in a subway storage room Friday produced heavy smoke, forcing the evacuation of a busy Manhattan station and disrupting rush hour service for tens of thousands of commuters, authorities said, Associated Press reported. Six firefighters suffered minor injuries, officials said. All seven train lines that were suspended due to the fire had resumed service by late morning, NYC Transit spokesman James Anyansi said. The trains still were bypassing West Fourth Street station, the major West Side subway hub where the fire occurred. The smoke rose through street grates, causing a heavy smoke condition at street level as well, said David Billig, a fire department spokesman. More than 100 firefighters and 25 pieces of fire equipment were at the scene, he said. The cause of the fire was not immediately known. Sixth Avenue was blocked off to traffic and crowds of onlookers snapped pictures on their cell phones. The smell of smoke wafted through the subway system, giving stranded riders a hint of the cause of their delay. Commuters covered their mouths with their hands as they rushed in and out of the trains. A fire in January that damaged a signal room knocked out service to two of the same lines for days.