20 demonstrators arrest thursday outside donald trump campaign rally southern california republican presidential front-runner vow supporters get tough illegal immigration elect demonstrators smash window police squad car march protest block traffic police riot gear try disperse crowd outside county fair ground costa mesa california accord local media twitter account orange county sheriff department department say twitter account 20 arrest make major injuries report trump visit costa mesa city 100,000 people third hispanic latino hop garner support california voters go poll state republican primary june 7. strong primary win california billionaire could thrust delegate count need secure republican nomination president avoid contest party convention july campaign stop thursday trump promise get tough illegal immigration build wall border mexico unite state popular theme presidential campaign suggest wall would stop drug come country drug poison youth lot people go get stop say tell crowd would force mexico pay wall event local news show hundreds demonstrators surround vehicles wave mexican flag hold sign protest trump outside orange county fair event center least one demonstrator show jump top police car demonstrators see shake police vehicle los angeles time reporter post photo twitter man wear trump t-shirt bloody face trump come fire rival fuel unrest rhetoric several rally around country meet protest last several months 20 demonstrators arrest outside trump rally california