The number of Chinese citizens coming across the southern border from Mexico has skyrocketed to the fastest-growing demographic of illegal immigrants in recent months, triggering serious concerns among lawmakers in Washington.

Tens of thousands of Chinese immigrants have been arrested by Border Patrol agents over the past year, far beyond the hundreds to a couple of thousand seen in recent history preceding the COVID-19 pandemic, according to Customs and Border Protection data. In 2022, fewer than 2,000 Chinese people were stopped at the southern boundary.