Massachusetts Attorney General Maura Healey is suing President Trump over his controversial executive order on immigration that she said strikes at the state's “lifeblood” in barring workers and students vital to its universities, medical centers and technology firms.

“Because of our people we have truly become a global state and a global leader,” Healey said. “That’s just one reason why this executive order is such a threat — because it threatens the vitality, the livelihood, the lifeblood, that drives so much of Massachusetts.”

Healey's message to Trump: “No one is above the law.”

“Our job in government and here in the attorney general’s office is to make sure that we uphold the rule of law, that we uphold the tenets and the principle set forth in our state constitution and our United States Constitution,” Healey said. “The executive order is unconstitutional and must be struck down, and we need to be prepared at all turns to take action as an office when and if someone acts in ways that are unlawful or unconstitutional.

“Whether it the president of the United States or a federal agency … we will be prepared to take action,” Healey said.

Flanked by business leaders, education officials and directors from advocacy groups, the Democratic attorney general blasted Trump’s immigration order as “harmful, discriminatory and unconstitutional,” and announced that she’d join a federal lawsuit filed in Boston on Saturday against the measure.

Republican Gov. Charlie Baker backed Healey’s action on behalf of the state.

“Massachusetts is a global community and we all benefit from the shared experiences of our partners from around the world to support our economy and educational institutions to make our state the best place to live, work and raise a family,” Baker said in a statement. “The recent executive order puts this at risk, will not improve our security, and the lack of guidance associated with such an abrupt and overwhelming decision is problematic for all involved.”

The executive order set off chaos at airports around the country this weekend as travelers, some with valid visas and even green cards granting permanent residency in the U.S., were detained or even deported — sparking thousands to take to the streets and protest the order nationwide. Last night, Trump fired Acting Attorney General Sally Yates, an Obama Administration holdover, when she ordered the Justice Department not to defend the order.

Healey cited the two Iranian UMass professors with green cards who were detained at Logan International Airport this weekend after the order was signed.

“With a wave of a pen, the president’s executive order kept them and thousands of others from coming home. The executive order barred people fleeing persecution and wars. It barred Iraqi interpreters who have assisted our military, and it barred students and researchers trying to get back to classrooms in Boston and across this country,” she said.

“The executive order is harmful, discriminatory and unconstitutional. It discriminates on the basis of religion and national origin, denies access to due process, violates immigration laws,” Healey said.

Legal challenges to the order resulted in federal judges in five cours around the country ordering a halt to deportations and detentions stemming from the order. Healey’s action joins a federal case in the U.S. District of Massachusetts that lawyers took to court today to add more complainants.

Healey was joined by UMass President Marty Meehan who said Trump’s order impacts hundreds of UMass students and staff and “undermines the mission of the University of Massachusetts, a mission that is critically important to this state and this country.”

“It pains and saddens me and I am big supporter of keeping our country safe,” Meehan told Boston Herald Radio. “I served in Congress and voted to strengthen of our laws to make the country safer but my grandparents immigrated to the U.S. from Ireland. We have always been nation of immigrants. I just think we need a more balanced approach.”

“It is not interest of the United States to have other countries in the world view us in this way,” Meehan added. “It is not in the interest of the United States as we look at issues of terrorism to operate this way — to not have the Secretary of Defense, Homeland Security, involved in these decisions.”

Meehan said there are 166 faculty and staff in the UMass system from the seven countries named in the Trump ban, which restricts immigration for 90 days and suspends the nation’s refugee program for 120 days. An estimated 300 students are from the seven nations, Meehan said.

“We are very concerned about it and its my job as president to do everything we can to protect those facility members, scholars, researchers, staff and students and make sure they are not unfairly detained,” Meehan told Boston Herald Radio today.

UMass Dartmouth associate professors Mazdak Pourabdollah Tootkaboni and Arghavan Louhghalam were detained Saturday evening after flying home from an academic conference in Paris. The two professors are Muslims, Iranian nationals, and lawful permanent residents of the United States. They were released after being detained for several hours.

“The complaint is being brought on behalf of the Commonwealth with specific allegations related to UMass,” Meehan said, noting MIT and the Massachusetts Hospital Association as other prominent institutions that have signed on.