Mexican protesters have blocked the Mexico-bound lanes at the main crossing in the twin border cities of Nogales to demand their government conduct strict coronavirus testing on Americans and other travelers entering the country

Protesters wearing face masks and carrying signs used a pair of vehicles to blockade the two southbound lanes on Wednesday at the DeConcini crossing, which links Nogales, Ariz., and Nogales in the Mexican state of Sonora, the Arizona Republic reported.

Some of the signs asked US residents to “stay at home,” while others called on Mexican President Andrés Manuel López Obrador to beef up controls and restrictions along the border to contain the spread of COVID-19.

The number of confirmed cases in the US is the third highest in the world and dwarfs the number of known cases in Mexico, where there has been little testing.

As of Wednesday afternoon, Arizona had confirmed more than 400 cases and at least six deaths resulting from the coronavirus, while Sonora had confirmed four cases of COVID-19 statewide.

Jose Luis Hernandez of Sonorans for Health and Life told the paper the blockade was the “first warning” for López Obrador.

“There are no health screenings by the federal government to deal with this pandemic,” he said.

“That’s why we’re here in Nogales. We’ve taken this action to call on the Mexican President Andrés Manuel López Obrador to act now.”

The group presented a set of demands, including a temporary ban on visits for tourism and medical procedures in Mexico for both Americans and Mexicans living in the States.

The group wants Mexican health officials to screen everybody crossing the border for symptoms of COVID-19.

“This is for your health. This is for your family,” Hernandez said. “Or what do you want to happen? That this becomes worse given the irresponsibility of the Mexican government? Of course not. That’s why were here.”

The protests came after years of tensions at the border as President Trump has repeatedly called for a crackdown on illegal immigration and construction of a wall along the border.

The Mexican government had earlier threatened to shut down the border over the pandemic.