A Milwaukee police officer was the target of accusations and online threats Tuesday from people who believe he shot the black man whose death sparked violence and days of unrest in the city.

Authorities have yet to identify the name of the officer who shot Sylville Smith on Saturday, but social media posts and at least one other news report identified him as a 24-year-old patrolman. Many posts contain threats against him and a photo.

According to the Milwaukee Journal Sentinel, at least 3,000 people have shared a Facebook photo of an officer they believe shot and killed Smith.

“Now y'all see his face if he's seen anywhere in the city drop him,” one scathing comment read, according to the Journal Sentinel. Another person wanted to “shoot him right in his head.”

Some others urged calm and to wait for all the facts to come out.

The Milwaukee Police Department said in a statement that it had noticed a “disturbing national trend” in which social media users have identified the officers involved in the police shootings and threatened them and their families. Police have only confirmed that the officer was black.

The department is aware of some local threats against its officers and is investigating, according to the statement.

Smith, 23, was shot and killed Saturday after a brief foot chase that followed a traffic stop. Police say Smith had a gun in his hand when he turned toward the officer, who opened fire. The state is investigating.

A few hours after the shooting, violence erupted on the city's largely black north side, with protesters hurling rocks at police and burning six businesses. A lighter night of protests followed Sunday. Monday was calm, though 10 people were arrested.

The Associated Press contributed to this report.