PORTLAND — Gov. Janet Mills denounced on Thursday the Trump administration’s ongoing immigration enforcement operations in Maine, likening federal officers to “secret police.”

At a news conference at Portland City Hall, Mills said federal officials have not given her office any data about how many arrests agents have made since the U.S. Department of Homeland Security launched what it calls “Operation Catch of the Day” on Tuesday.

The administration is targeting about 1,400 people in the state, federal officials have said. But Mills doubted their claim that officers are only arresting those who have criminal records.

“We’ve reached out. We’ve asked questions. We have no answers,” said Mills, a Democrat.

Maine Republicans warned Thursday that Democrats should cool their rhetoric and not impede law enforcement.

“We need to sit down together and talk — not past each other — about how Maine moves forward,” Assistant House Minority Leader Katrina Smith, R-Palermo, said in a weekly radio address. “Leadership means lowering the temperature, not raising it.”

The Trump administration said officers began operations in Maine on Tuesday to target what officials called “the worst of the worst” criminals who are in the U.S. illegally.

“Gov. Mills and her fellow sanctuary politicians in Maine have made it abundantly clear that they would rather stand with criminal illegal aliens than protect law-abiding American citizens,” Assistant Homeland Security Secretary Tricia McLaughlin said in a statement earlier this week.

However, the 50 initial arrests that federal agents made Tuesday included several people who do not have criminal records. Mills said she would be “shocked” if Maine is home to 1,400 people with criminal records who are in the country illegally.

As Mills spoke Thursday, reports and videos continued to roll in of ICE agents moving about in Portland, Westbrook and South Portland. One video showed agents grabbing a man from a vehicle by the University of Southern Maine’s Portland campus. The governor criticized federal officers for wearing masks that conceal their identity.

“In America, we don’t believe in secret arrests or secret police,” Mills said. “God, that goes back to the Magna Carta, doesn’t it? And it’s one of the foundations of our country and our Constitution.”

Mills said she didn’t have a message for Trump. But she noted the Trump administration has targeted blue states with its higher-profile immigration enforcement efforts.

“Why Maine? Why now?” asked Mills, who’s running for U.S. Senate. “What were the orders that came from above?”

Local and state Democratic officials have largely joined Mills in airing concerns about Immigration and Customs Enforcement activity.

Portland Mayor Mark Dion stood off to the side while Mills spoke to reporters Thursday. Later in the day, Dion met with U.S. Sen. Angus King, an independent who caucuses with Democrats. Like Mills, King said he had little information from the Trump administration to share with local officials.

“Let’s call this what it is: this is a large-scale mass deportation effort,” King said. “Let’s drop the pretense that somehow this is about the worst of the worst.”

Mills’ appearance came after it was reported that on Tuesday, the day federal agents began their operation, Mills was thousands of miles away at an event in California.

It’s not clear what she was doing there. Mills’ office referred a request for comment to her Senate campaign. A spokesperson for the campaign did not answer questions about the nature of the event, which was first reported by the Bangor Daily News.

The spokesperson said Mills was “traveling for a previously scheduled event.”

Staff Writer Reuben Schafir contributed to this story.