San Francisco Municipal Railway service had resumed between Van Ness and West Portal stations by about 4:40 p.m. Thursday after report of smoke under a platform.
The smoke was reported around 3:15 p.m., spokeswoman Kristen Holland said.
Route adjustments were made to several Muni lines and bus shuttles were deployed to allow riders to reach their destinations.
All Muni customers were evacuated from the Castro Station, Holland said.
After the scene was cleared, shuttles were scheduled to remain in service through the evening commute hours, according to Holland.
-Bay City News Service