The San Diego Police Department declared a demonstration in Pacific Beach an unlawful assembly Saturday "due to acts of violence."
Roughly 50 pro-Trump and 200 anti-Trump demonstrators squared off Saturday afternoon at Hornblend Street and Mission Boulevard.
Officers said they were struck with rocks, bottles and eggs at a gathering featuring demonstrators for and against President Donald Trump in Pacific Beach.
"Please clear the area and head away from the scene," police also tweeted.
A pro-Trump "Patriot March'' had been announced for 2 p.m. but counter-protesters arrived earlier and began chanting.
The two protests began near the entrance to the Crystal Pier at 4500 Ocean Blvd. at about 1 p.m. Saturday, and by 3:40 p.m., crowds from both sides began to disperse.
As more police arrived on the scene, some marching down Mission Boulevard and some riding bikes, they took up positions to separate the Pro-Trump protesters and a group of Black Lives Matter and Antifa protesters.
"Those who remain or return against this lawful order may be cited/arrested and risk exposure to chemical agents & less-lethal force applications," police told the two groups. There were reports of some protesters being pepper-sprayed.
In a video posted online, a group of black-clad protesters, one displaying an "Antifascist Action" banner, could be heard chanting "racists go home" at the entrance to Crystal Pier.
At least one person was arrested but there were no immediate reports of injuries.
