PHILADELPHIA (WPVI) -- An underground fire is causing a blackout in Philadelphia's University City section Tuesday morning. It happened around 4:30 a.m. in the 3100 block of Market Street. The fire caused a manhole cover to explode, cutting power for two blocks, according to officials.

The outage began along Market Street when underground cables overheated around 4:30 a.m., according to a PECO spokesperson. The issue led to a power outage initially impacting about 500 customers in and around University City, including 30th Street Station, with is currently operating on a backup generator.

The power has gone out for a second time on Market Street in Philadelphia's University City section early Tuesday morning.