Director of Homeland Security Tom Ridge sent a powerful message to Americans Thursday: They should feel confident in the government and its response to terror threats real and imagined. 

Ridge said his objective will be to provide clear, concise, and comprehensive information to the public while looking for ways to protect America. It was his first press conference since being sworn into office on Oct. 8. He has been given the difficult task of creating a staff pulled from among the personnel of 50 different federal agencies. 

Ridge spoke along with Attorney General John Ashcroft, FBI Director Robert Mueller, Surgeon General David Satcher and Dr. Mitch Cohen from the Centers for Disease Control. Also present were Secretary of Health and Human Services Tommy Thompson, Postmaster General John E. Potter, Deputy Surgeon General Rear Admiral Kenneth P. Moritsugu and General John Parker, of the Army Medical Research Institute for Infectious Diseases. 

Ridge said President Bush has given him the authority to conduct collaboration and communication, but added that he does not have tactical or operational authority. 

"I have been cleared by the president to have as much information as I want or need," he said. 

Ridge added that thousands of people have been tested for exposure and thousands of environmental searches have been done. Five people have contracted anthrax diseases in New York and Florida, the latest at CBS News, and a sixth is being confirmed. 

Thirty-one people in Washington have been tested positive for possible exposure to the bacterium. All are on antibiotics for precautionary measures, and the drugs used to treat infected patients seem to have an effect on the anthrax strains. 

The exposures have given rise to two priorities, said Ashcroft. 

"First, to use the information we have about these cases to do what we can to prevent further harm," he said. "Second, we are aggressively searching for the source of the bacteria and for the person or people responsible for the criminal acts of dispersing and sending these bacteria in the mail." 

To that end, Mueller announced the United States Postal Service and the FBI are offering a $1 million reward for information leading to the arrest and conviction of those responsible for the anthrax mailings. Ashcroft said four arrests have been made for sending phony anthrax. 

The U.S. Postal Service is also sending postcards to every home in America to teach the public what clues to look for when they receive suspicious mail. 

The government's response to the anthrax outbreak emphasizes the importance of coordination between federal and local agencies, Ridge said. To increase that coordination, Thompson, Surgeon General Satcher and the CDC will confer with health care professionals. 

The government's response, said Satcher, has been on target. 

"We believe the public health infrastructure is responding very well to this threat," he said. 

Ridge thanked the American people for their strength and understanding during this difficult time, and reassured them that while the government seems preoccupied with the anthrax scare, it is responding on all fronts to prevent attacks on America. 

"I mean, if you take a look at everybody in the FBI, the Border Patrol, the Coast Guard, CDC, everybody is working 24-7," he said. "We've engaged the state and the federal communities. I think our antenna are up for all conceivable risks and you ought to be reassured of that." 

Fox News' Catherine Herridge contributed to this report.