About 500 people protested outside Los Angeles police headquarters on Sunday over the shooting death of an unarmed black man in California as disturbances continued in Missouri over the police killing of a black teenager there last week.

Ezell Ford, 25, was killed by police in Los Angeles on Monday, two days after 18-year-old Michael Brown was shot dead by a police officer in the St. Louis suburb where he lived.

"He was a humble guy," said Ford's cousin, Ceebo Ship, 22.

Ship and other family members said Ford suffered from an unspecified mental illness and was "slower than the rest of us," and a gentle person who loved basketball.

Ford's family said he was cooperating with officers and lying on the ground when shot. The Los Angeles Police Department said Ford had struggled with officers and was trying to grab one of their guns when he was shot.

The protesters remained peaceful on Sunday, many holding up signs that read, "Hands up, don't shoot," in reference to witness reports that Brown had his hands up when he was shot dead on Aug 9. Drivers honked their horns as they went by.

Los Angeles police are investigating Ford's death, which took place during an investigative stop that led to a scuffle, a police spokeswoman said.

The Los Angeles Police Department said no officer was hurt in the incident, and Ford, who was identified by family members, died in a local hospital.