Update: Muni service is returning to normal.
SF Muni is reporting a major delay this morning after a man was struck and killed by a train. The Chron reports:
An inbound N-Judah train hit the man while he was walking in the tunnel 700 feet east of the station platform shortly before 7:30 a.m.
Officials said it is unclear why the man was in the tunnel. He was declared dead at the scene, and the station will be closed while the city's Medical Examiner's office conducts its investigation. Full article
Here's more info from Muni:
On Friday November 2 at 8:15 am, SF Muni reports a service suspension of all Metro service between the West Portal and Embarcadero stations due to a medical emergency. Shuttles are in place. The N and J Lines are switching back at Duboce Street.
Muni riders with valid Muni tickets may enter BART between Balboa Park and Embarcadero stations this morning for free until further notice. They must have their ticket in their possession and show it to the Station Agent. If they travel farther, they will need to pay the prorated fare for that distance.