Residents in Sonora, south of the US state of Arizona, have promised to block traffic into Mexico for a second day after closing a checkpoint for hours on Wednesday.
They wore face masks and held signs telling Americans to "stay at home".
Mexico has fewer than 500 confirmed Covid-19 cases and the US over 65,000.
HAHAH MY MY MY HOW THE TURNTABLES
Americans flood into Mexico in search of toilet paper, food, water
TIJUANA (Border Report) — Desperate Californians are flooding into Northern Baja in search of water, toilet paper and other essential items.
An hour before the Costco in Tijuana opened Tuesday morning, there was already a line forming. Employees said that in recent days, there have been 600 people in line by 10 a.m. They know this because the store only has 600 shopping carts — and those have all been taken.
