Large smoke plume snarls Center City traffic
A large plume of smoke is billowing from two sidewalk grates near Ninth and Arch streets in Center City.
Police and fire officials said they first began receiving calls about the incident around 4:30 p.m. Monday.
Authorities are not yet sure what is causing the cloud of smoke, but emergency crews are on the scene investigating.
Commuters reported the steam was compounding delays during rush hour traffic Monday evening.