Arizona Congressman Raul Grijalva tested positive for Covid-19, his office announced on Saturday.

Grijalva, a Democrat whose district includes parts of the Phoenix and Tucson areas, as well as much of the state's border region with Mexico, is self-isolating in the Washington, D.C., area, according to spokesman Geoff Nolan. 

In a statement, the congressman criticized some other members of Congress for not taking the virus seriously and he praised House Speaker Nancy Pelosi's decision to require masks. 

"While I cannot blame anyone directly for this, this week has shown that there are some Members of Congress who fail to take this crisis seriously," Grijalva said in the statement. "Numerous Republican members routinely strut around the Capitol without a mask to selfishly make a political statement at the expense of their colleagues, staff, and their families."

The news about Grijalva's positive test was first reported by the Arizona Republic, which said that Grijalva presided over a committee meeting on Tuesday that included Texas Rep. Louie Gohmert. Gohmert announced on Wednesday that he had tested positive for the virus. 

Grijalva appears to be the 12th member of Congress to test positive for Covid-19. There have been more than 4.5 million confirmed cases of the virus and at least 153,000 deaths in the United States, according to data from Johns Hopkins University.