PHILADELPHIA—A Philadelphia utility company says power has been restored to almost all the hundreds of customers affected by an outage related to underground electrical cables that caught fire.

A Peco spokeswoman says nearly 800 customers lost power early Wednesday but service has been restored to all but three: an apartment building and two businesses.

She says the cables are more damaged than expected but that power should be restored to the apartment building sometime Thursday morning. Crews will then begin determining what is needed to start restoring power to the businesses.

Firefighters say the 10-story apartment building was evacuated after the underground blaze sent smoke through it. No injuries have been reported.