Mexican citizens come to renew passports that have been unused for more than a decade. They desperately ask lawyers if they can do anything to help them stay in the United States. They register their children for Mexican citizenship, just in case they are sent back and decide to move their whole family with them.

When the consulate began to get reports of dozens of Mexicans being arrested by immigration officials last week, they immediately dispatched lawyers to the federal detention center downtown. Officers closely monitored social media, simultaneously trying to get information and quash unfounded rumors. In one case, they helped a man whom immigration officials had quickly sent to the border for deportation return to Los Angeles for a hearing in immigration court…

In the last week, the Mexican government has created a 24-hour hotline to help answer any questions for Mexicans in the United States. Last month, Mexican President Enrique Peña Nieto announced that he would spend $50 million to pay for lawyers at every consulate to help people facing deportations. And consulates have been distributing fliers detailing what to do if someone is approached by deportation agents — advising them not to open their doors without proof of a warrant or speak to officers without a lawyer.

Foreign service officers who have spent decades in the United States said in interviews that they had all encountered increased anxiety among undocumented immigrants, as several states have passed their own laws to deal with illegal immigration. But they said this was the most hostile national atmosphere for Mexicans in recent memory, making their jobs both more difficult and more urgent.