OAKLAND, CALIF. >> A federal law enforcement officer in California was killed and another critically injured after being shot while providing security at the U.S. courthouse in Oakland near one of the increasingly violent protests unfolding around the country.

“When someone targets a police officer or a police station with an intention to do harm and intimidate — that is an act of domestic terrorism,” Department of Homeland Security Acting Deputy Secretary Ken Cuccinelli said at a Washington, D.C., news conference on today.

The Oakland shooting occurred after a vehicle pulled up outside the Ronald V. Dellums Federal Building at about 9:45 p.m. Friday. Someone opened fire at two contract security officers who worked for Homeland Security’s Federal Protective Service, killing one and critically wounding the other, authorities said.

The officers protect federal court houses as part of their regular duties. DHS officials said they were monitoring the Oakland protest over the police killing of George Floyd in Minnesota.

The identities of the officers have not been released.

A suspect hasn’t been named and it wasn’t immediately known whether authorities have determined if the shooting was connected with the protest.

Federal officials said they’re seeing more threats and assaults against law enforcement officers at protests and said they will step up security measures to protect them.

“There are currently threats by some to attack police stations and federal buildings, Cuccinelli said. “That violence not only won’t be tolerated, we are also committed to ensuring that it won’t succeed anywhere, anywhere.”

The protest in downtown Oakland began peacefully but spiraled into chaos late into the night. Some demonstrators smashed windows, set fires and threw objects at officers. Police said 13 officers were injured.

The federal building’s glass doors were smashed and the front entrance was sprayed with anti-police graffiti.

California Sen. Dianne Feinstein condemned the violence,

“We have to know right from wrong and not use the terrible tragedy in Minneapolis to perpetrate more violence.” she said “There’s never an excuse to shoot and kill a security guard, destroy businesses or injure innocent people.”