“They have that intention,” Sergio Tamai, a founder of Angels without Borders, a group helping the migrants, told Telemundo 20 in San Diego. “I believe that thousands could make that jump.”

At least 3,000 migrants have already arrived in Tijuana, a border city across from San Diego, Calif., the past two weeks. The federal government estimates the number of migrants could grow to 10,000 in the coming weeks, or months.

Those already in the city have camped out in tents, slept on dirt fields or under bleachers or are staying in overcrowded shelters throughout the city as they wait to figure out their next steps.

But some are growing impatient, and believe their best option is to plan a mass crossing.