Authorities in Philadelphia say a damaged power line led to an underground explosion yesterday.
The 5:15 pm blast lifted three manhole covers off their bases and sent smoke billowing up in University City.
The Philadelphia Daily News says no injuries or power outages were reported.
PECO spokeswoman Cathy Engel-Menendez says the damaged line feeds into the city grid but does not directly provide electricity to nearby homes or businesses.
She said the cause of the damage to the power line was not immediately clear. Technicians will be in the the area again today to start making permanent repairs.