2 more black men killed by police in U.S. amid nationwide protests

There have been two more instances of police shootings of black menin the U.S., one in Texas on Saturday and one in California on Monday.

In both cases, police say the men were wielding weapons. Alva Braziel, 38, was killed in Houston, Texas,on Saturday, allegedly while pointing a gun. An unnamed man, armed with a knife, was killed Monday in Sacramento, Calif.

In Houston, activists have pointed tounconfirmed surveillance footage, which appears to show the suspect with both hands up when officers fire on him.The clip is dark andshot from a distance, so it is unclear whether he has anything in his hands.

• WARNINGThis video contains disturbing images: AlvaBraziel video

The deaths come as protests and related events continue across the countryafter the police shootings of Alton SterlinginBaton Rouge, La., Philandro Castile insuburban St. Paul, Minn., and thedeadly sniper attack on police officers in Dallas.

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Two police officers fatally shot a knife-waving man Monday during a confrontation on a street in Sacramento,authorities said.

The shooting occurred after witnesses called police to report that a man was waving a knife over his head and showing "very threatening, erratic behaviour," police spokesman Sgt. Bryce Heinlein said.

One witness told police the man had a gun in his waistband, Heinlein said.

The man threw an object at a police vehicle and was seen reaching for his waistband as if he was trying to retrieve a weapon, the Sacramento Police Department said in a statement.

It also said the man later raised a knife over his head while charging one officer who locked himself in his patrol car to escape injury.

Two more officers arrived and eventually shot the man when he turned toward them with the knife, Heinlein said. A news release said officers fired "multiple" shots.

Officers later found a folding knife but no gun, he said.

'Non-compliant'

"He was non-compliant throughout the whole ordeal," refusing repeated commands to drop the weapon, Heinlein said. "I'm not sure if he came at the officers ... but he turned toward the officers in a threatening manner and at that point the officers fired."

The man was shot on a sidewalk while the two officers were close to him, said Officer Matthew McPhail, another police spokesman.

The man was not immediately identified. Police described him as black and in his 50s or 60s.There was no indication he was targeting police officers, Heinlein said.

"It's more erratic behaviour," he said of the circumstances. "At this point I don't know what his mental stability was."

Witness Alton Ford told The Sacramento Bee that officers tried to calm the man without success.

"He was cussing at them," Ford said. "They gave him plenty of opportunity."

The names of the officers involved in the shooting were not immediately released. One has 25 years on the force, and the other has 22 years.

They were not wearing body cameras and apparently did not try to use less-lethal force before they opened fire, Heinlein said.

An officer was injured during the pursuit but not by the suspect, Heinlein said. The officer was later released from a hospital.

Houston shooting captured on security camera

The Houston mayor is asking the U.S. Justice Department to review the fatal police shooting of a man who authorities say had pointed a gun at officers.

Mayor Sylvester Turner also said Monday that since "tensions are running high," he recommends all available video be released as soon as possible.

Turner says video from a gas station shows that just before police arrive on Saturday, Alva Braziel appears to fire two shots in the air and then raise his arms and turn in a circle.

He says after police arrive, he sees Braziel step toward them with his right arm extended toward them.

He says that in video not yet made public, a bystander acknowledges Braziel had a gun. A gun was taken from Braziel's right hand by an officer.

Activists and community leaders say they are monitoring the investigation.

The Houston chapters of the NAACP and Black Lives Matter say they're waiting for more details about the Saturday shooting.

Some people say surveillance video from a nearby gas station, which has been circulating on social media,shows Braziel had his hands up before being shot.

The video is dark and it's hard to see clearly whether Brazielhad anythingin his hands and what happened in the moments before officers fired.

Houston police spokeswoman Jodi Silva said Sunday her agency is asking people to withhold judgment until all the evidence is reviewed.