A gunman carjacked a valet who was watching over a black Porsche near San Francisco’s Embarcadero, police said.

At about 3:50 p.m. Monday, a valet watching the 2-door Porsche Carrera on the 400 block of Spear Street told a man to stop leaning on the sports car because it didn’t belong to him. In response, the man lifted up his shirt, revealing a black semiautomatic handgun, police said.