SAN FRANCISCO (CBS SF) — Four demonstrators were arrested and five vehicles seized after an immigration protest blocked lanes on the Golden Gate Bridge Thursday, bringing the morning commute into San Francisco to a halt for more than 30 minutes.

The demonstration — organized by the Bay Area Coalition for Economic Justice and Citizenship for All — used a vehicle caravan to block lanes, calling attention to their demands for change to U.S. immigration policies.

READ MORE: Flash Flood Watches Issued As Storm Aims at Fire-Scarred Northern California

The caravan halted traffic around 7:20 a.m. and a massive banner reading “Override The Parliamentarian” was stretched across the lanes heading into San Francisco. The California Highway Patrol shut down the lanes heading into Marin as a precaution.

From a flatbed truck, organizers delivered their message via a megaphone and unfurled a banner critical of Vice President Kamala Harris’ handling of immigration policy.

READ MORE: Amid the Capitol Riot, Facebook Faced Its Own Insurrection

The CHP said the lanes had been cleared by 7:53 a.m. but by that time the backup into the city stretched for miles into Marin County.

They said they had arrested four protestors and towed five vehicles.

MORE NEWS: US Rowing Accepts Resignation of Longtime Men's Coach Mike Teti

No other information about the protest was immediately available, but organizers are also planning a noon rally in San Jose.