Protest moves through Downtown Los Angeles during potentially "historic storm"

A protest moved through Downtown Los Angeles as an atmospheric river carrying the potential of "life-threatening flash flooding" poured rain on demonstrators.

The Los Angeles Police Department said they are monitoring the demonstration and advised motorists to avoid the area if possible. Drivers should expect delays. 

"We are aware of a protest in Central Area," the department tweeted. "This is causing traffic delays. We are monitoring to ensure everyone's 1st Amendment right is protected."

A flyer advertised the "Shut it Down for Palestine" protest with the tagline "No Grammy Celebrations in Our Streets" starting at Pershing Square at about 2 p.m. 

Mayor Karen Bass described the storm as a "serious weather event."

"This has the potential to be a historic storm, severe winds, thunderstorms, and even brief tornadoes," Bass said during an afternoon news briefing.