The Transportation Department says it will immediately tighten up the requirements for non-citizens to get commercial drivers licenses after three fatal crashes this year in Florida, Texas and Alabama.

Officials say those crashes were caused by immigrant truck drivers who never should have received licenses.

The nationwide audit of these licenses began after a fatal U-turn crash in Florida that killed two people caused by a truck driver who officials said was in the country illegally.

Transportation Secretary Sean Duffy said also threatened to revoke $160 million in federal funding for California because investigators found that one in four of the 145 commercial drivers licenses for non-citizens issued since June should have never been issued.