Hurricane Dolly has made landfall in Texas, bringing winds of up to 160km an hour and heavy rain to coastal areas of the state and northern Mexico.
A category two hurricane warning is in place from Brownsville to Corpus Christi and from Rio San Fernando northward in Mexico.
Dolly, the second hurricane of the 2008 season, was upgraded from a tropical storm to a category one hurricane on Tuesday afternoon, before being upgraded again to category two status on Wednesday morning.
Towns and cities in the Rio Grande Valley are on alert in case of flooding.
In Cameron county, 2000 people have been moved to temporary shelters.
Texas Governor Rick Perry has called up 1,200 National Guard members as a precaution.
Mexican authorities say they have evacuated more than 13,000 people in Tamaulipas state. As many as 10,000 more refused to leave.