SAN DIEGO, Calif. --A demonstration outside the Donald Trump rally in San Diego turned rowdy Friday, as some protesters began screaming, throwing water bottles and trying to scale a barricade.
Police declared an unlawful assembly and officers in riot gear worked to clear the streets in the historic Gaslamp Quarter, near the San Diego Convention Center where Trump appeared.
At least three people were arrested, police said.
Clashes began after Trump supporters began leaving the convention center around 4 p.m. Protesters and supporters began arguing and yelling at each other. At one point, the two sides surrounded a patrol car and began screaming and hurling empty water bottles at each other.
Many of the protesters' signs were about Trump's plans to build a wall along the Mexico border.
After one of the protesters was arrested for trying to breach a secured area, some in the crowd began spraying water and throwing empty plastic bottles at police.
About 1,000 protesters were estimated in the various crowds.
Inside the event, Trump was greeted warmly by supporters. He offered praise for Sen. Bernie Sanders, who continues to battle Hillary Clinton in the Democratic primary.
"Bernie Sanders has been great," Trump said. "We like Bernie. ... He doesn't have a chance and what he's doing to her is incredible."
Sanders and Clinton are expected to continue campaigning hard in California leading up to the state's June 7 primary. Trump has already secured the delegates he needs for the GOP nomination, but has been making multiple appearances in California as well.
Earlier Friday, Trump appeared in Fresno. Protesters also greeted him outside that event, but the demonstrations were peaceful with no arrests.