House Speaker Paul Ryan called the action "appropriate and just."
"Earlier this week the Assad regime murdered dozens of innocent men, women, and children in a barbaric chemical weapons attack. Tonight the United States responded," he said in a statement. "... These tactical strikes make clear that the Assad regime can no longer count on American inaction as it carries out atrocities against the Syrian people."
On Tuesday, a chemical weapon attack on a Syrian town killed at least 86 civilians. Blame for the assault has landed on Syrian President Bashar al-Assad despite the Syrian government's condemnation of the attack and insistence that rebels fighting in the country's civil war were at fault. The Turkish Health Ministry later determined that sarin gas was used in the attack, based on autopsies of some of the victims.
Thursday evening's airstrike, which targeted Shayrat Air Base in Homs Province where a chemical attack was initiated earlier in the week, struck multiple targets with missiles launched between 8:40 and 8:50 p.m. ET from the destroyers USS Porter and USS Ross in the Mediterranean Sea
Sen. Marco Rubio, R-Florida, called the strike an "important decisive step."
"It is not a message," he said. "It is a degrading of the capability of the Syrian regime to carry out further chemical attacks against innocent civilians."
Senate Minority Leader Chuck Schumer, D-New York, said, "Making sure Assad knows that when he commits such despicable atrocities he will pay a price is the right thing to do."
He added: "It is incumbent on the Trump administration to come up with a strategy and consult with Congress before implementing it. I salute the professionalism and skill of our Armed Forces who took action today."
Some criticized Trump's response.
Sen. Rand Paul, R-Kentucky, tweeted, "While we all condemn the atrocities in Syria, the United States was not attacked."
He continued: "The President needs Congressional authorization for military action as required by the Constitution."
Rep. Ted Lieu, D-California, said, "This was done with no debate in Congress & no explanation to the American people," he wrote on Twitter. "Assad is still in power. What was purpose of strike? How much did this cost? Was Assad a threat to US homeland? How does this achieve peace?"
Lieu added that Trump "campaigned to get US out of foreign wars. His actions in Syria, Iraq & Yemen show he is acting like a warmonger."
Rep. Seth Moulton, D-Massachusetts, hit Trump over his refugee stance. "So @POTUS cares enough about the Syrian people to launch 50 Tomahawks but not enough to let the victims of Assad find refuge & freedom here," he tweeted.
Sen. Chris Coons, D-Delaware, said he was "encouraged that the Trump administration has felt compelled to act forcefully in Syria against the Assad regime," but added that he was "gravely concerned that the United States is engaging further militarily in Syria without a well-thought-out, comprehensive plan."
"Frankly, the president’s actions today generate more questions than answers," he added.
Following the strike, Trump gave a statement, offering harsh words for Assad and speaking about the cruelty of seeing innocent children tortured.
"It is in this vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons," he said in part. "There can be no dispute that Syria used banned chemical weapons, violated its obligations under the chemical weapons convention and ignored the urging of the UN Security Council."
ABC News' Arlette Saenz, John Parkinson, MaryAlice Parks, Ali Rogin, David Caplan, Paul Blake and Adam Kelsey contributed to this report.