Demonstrators gathered outside the Police Department in El Cajon, Calif., on Wednesday morning calling for a federal investigation into the fatal police shooting of a black man a day earlier, the latest in a string of such killings that have provoked protests nationwide.

The man, whom the police identified as Alfred Olango, 38, was walking in traffic and said to be acting “erratically.” A responding officer fatally shot Mr. Olango after he pulled an object from his pocket, the police said. On Wednesday night, the police identified the object as a vape smoking device with a silvery cylinder the police said “was pointed toward the officer.”

Agnes Hasan, a close friend of Mr. Olango’s family and one of many who spoke outside the police station Wednesday, said that Mr. Olango was from Uganda and that his family and hers had been together in a refugee camp.

“We came to this country to bring our kids, to give them better education and a better future,” she said. “This guy went to school, he finished school. He’s an educated man. We suffered too much with the war in Africa. We come here also to suffer again?”