A San Francisco streetcar full of passengers travelled for a short time late this morning with no operator on board.  

According to the San Francisco Municipal Traffic Agency, the operator of the MUNI Metro streetcar had gotten out of the "K-Ingleside" train to look at a malfunctioning door.

A report in the "San Francisco Chronicle" says the operator may have failed to set the emergency brake.  

The train was brought to a halt in the tunnel between the Castro and Forest Hill Stations by a passenger who activated the emergency brake.

Officials say streetcars run under automatic control along that stretch so no one was ever in danger.  

The driver has been place on adminstrative leave while the incident is being investigated.