A man in his 50s was fatally assaulted late this afternoon on Larkin Street between O'Farrell and Ellis.

Officers on the scene said that it's currently not known whether the victim, who goes by the name Milkshake, was assaulted with a weapon. The motive behind the assault was not yet known either, and no arrests have been made.

Investigators are currently canvassing the scene. At approximately 4:45pm, officers expected Larkin Street between O'Farrell and Ellis to remain closed to all vehicle and pedestrian traffic for roughly two-and-half to three hours as the investigation continues.

Residents of the block were not being permitted to enter or exit the area until the investigation finishes, but one officer at the scene said that disabled people and seniors could potentially be escorted to their front doors.

The 38-Geary bus continues to operate normally down O'Farrell Street, but the 19-Polk bus, which runs down Larkin Street from Civic Center to Geary, is being rerouted.