Some protestors in Hollywood clashed with police and seven people were arrested on charges including resisting arrest, public intoxication, and battery. One protestor jumped on top of a police car. He was quickly thrown to the ground and arrested.
Overall, the demonstrations were mostly peaceful.
"There were a thousand or more people gathered on the street. We marched down to the CNN building, we marched over to Hollywood and Highland, and then back here. The police have been wonderful. They've been protecting us the whole way. It's an amazing crowd, and we're here for the right reason," said Paul Asplund, an opponent of Prop 8.
Over the weekend the 'Yes on 8' campaign held rallies supporting the measure.
Petitions have already been filed asking the state Supreme Court to invalidate Prop 8.
Supporters expected the constitutional amendment will survive any legal challenges.
"We accept this win, and it was a great moment for California. The voice of the voters has spoken and has been heard not once, but twice. And they very much want to uphold traditional marriage," said Sonja Eddings-Brown, 'Yes on 8' Deputy Communications Director.
About 18,000 gay couples married since a state Supreme Court ruling in May. The state attorney general, Jerry Brown, has said those marriages will remain valid, although legal challenges are possible.
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