Police officers in El Cajon, a city near San Diego, shot and killed an unarmed black man, prompting crowds to gather at the scene and authorities to call for calm.

Police officers in El Cajon, a city near San Diego, shot and killed an unarmed black man, prompting crowds to gather at the scene and authorities to call for calm, less than two weeks after similar incidents in two other U.S. cities.

In Tuesday afternoon’s incident in El Cajon, two officers responded to calls that an African-American man in his 30s was walking in traffic and “not acting like himself,” El Cajon police said.

Days earlier, in Charlotte, North Carolina and in Tulsa, Oklahoma, police and shot and killed black men, igniting protests against racial bias in U.S. policing and demands for greater accountability for officers.

In Charlotte, rioting prompted the authorities to impose a state of emergency and curfew.

Officers found the man behind a restaurant at about 2 p.m. PDT (2100 GMT) and ordered him to remove his hand from his pocket, police said. After he refused, one officer drew a firearm and the other readied a Taser device, police said.

The man paced back and forth as the officers tried to talk to him with their weapons pointed at him, police said.

Moments later, he pulled an object from his front pants pocket, placed both hands together and extended them toward an officer in “what appeared to be a shooting stance,” police said.

The officers then simultaneously shot and used the Taser on the man, who died after being taken to the hospital, police said. Officials have not identified him.

No weapon was found at the scene, El Cajon Police Chief Jeff Davis told a news conference hours after the shooting. He did not said what the man was pointing. The officers were placed on administrative leave, which is standard procedure in such incidents.

“Now is a time for calm,” Davis said. “I implore the community to be patient with us, work with us, look at the facts at hand before making any judgment.”

Crowds gathered through the night at the scene and at the El Cajon Police Department, where they demanded information, local media showed.

Video emerged on social media purportedly from the moments after the shooting. In the footage, a woman who says she is the victim’s sister is heard saying that she phoned police.

“Oh my God. You killed my brother. I just called for help and … you killed him,” the unidentified woman said, sobbing.

A bystander voluntarily provided investigators with cell phone video that captured the incident, police said.

Police released a still photo from the video that appeared to be two officers pointing weapons at a man who was aiming an object at them.

In a statement, the San Diego chapter of the American Civil Liberties Union called for a swift and transparent investigation. They also condemned “disturbing” reports that police officers had confiscated witnesses’ cell phones.

The San Diego District Attorney was investigating the shooting, police said. El Cajon, with population of about 100,000 people, is about 15 miles northeast of San Diego.

A study released in July showed police used force on black people at rates more than three times higher than for whites.