A spokesman for U.S. Sen. John Cornyn says authorities are investigating a suspicious letter sent to a district office.
Cornyn spokesman Drew Brandewie says authorities have been called to his office in Farmers Branch, just north of Dallas. He declined to provide more information.
A message left for Farmers Branch police was not immediately returned.
Authorities are investigating a series of suspicious letters being sent to offices around the country, including two letters sent to President Obama and a Mississippi senator that have tested positive on a preliminary basis for poison.