Arizona’s Sen. John McCain (R) said illegal immigrants may have started some of the wildfires that have forced thousands of people from their homes in his state, but he did not give evidence to support the statement.

“There is substantial evidence that some of these fires have been caused by people who have crossed our border illegally,” McCain said at a Saturday press conference after touring the area around where the Wallow fire burns in southern Arizona.

“The answer to that part of the problem is to get a secure border.”

U.S. Forest Service spokesman Tom Berglund said on Sunday that he was not aware of any evidence that illegal immigrants had set the fire that McCain was visiting.

“Senator McCain was referring to fires on the Arizona/Mexico border, not the Wallow fire,” McCain spokeswoman Brooke Buchanan wrote in a press release Monday.

McCain did not say what evidence he was referring to at the press conference, but he offered reasons why he believed that illegal immigrants had set outdoor fires.

“They have set fires because they want to signal others; they have set fires to keep warm; and they have set fires in order to divert law enforcement agents and agencies from them,” he said.

McCain’s remarks drew condemnation from Latino civil rights groups, many of which are fighting Arizona’s strict new immigration law.

Wildfires in southern Arizona have forced the evacuation of 10,000 people from 4,300 homes, according to the Associated Press.