US President Barack Obama makes a statement in the Brady Briefing room at the White House April 23, 2015 in Washington, DC. President Obama talked about a US drone strike that targeted a suspected al Qaeda compound in Pakistan but inadvertently killed an American and Italian being held hostage by the group. Mark Wilson/Getty Images

President Barack Obama apologized Thursday morning for the U.S. government's accidental killing of two innocent hostages of al Qaeda during a counterterrorism operation in January in the Afghanistan-Pakistan border region. He named Dr. Warren Weinstein, an American, and Giovanni Lo Porto, an Italian, as the victims.

"There are no words that can ever equal their loss," Obama said in a statement delivered at the White House. "As president and as commander-in-chief, I take full responsibility for all our counterterrorism operations, including the one that inadvertently took the lives of Warren and Giovanni." He added that he offered his "deepest apologies to their families" on behalf of the U.S. government.

"We are devastated by this news and the knowledge that my husband will never safely return home," Elaine Weinstein, the widow of Warren Weinstein, said.

Obama did not mention two other Americans, working with al Qaeda, who were also killed, as the White House announced Thursday. One, Ahmed Farouq, was a leader of the organization and was believed to have been killed in the same operation as the hostages, while Adam Gadahn, a top member of al Qaeda, was killed in a separate operation. The government said neither of them had been specifically targeted by the operations, as the White House did not know where they were at the time.

"We believed that this was an al Qaeda compound, that no civilians were present," the president said, adding, "we do believe that the operation did take out dangerous members of al Qaeda." The operation was classified until Thursday, when Obama directed that the information be declassified and shared publicly after speaking to Weinstein's family as well as Italian Prime Minister Matteo Renzi.

The president also spoke in more abstract terms about the tragedy of civilian deaths during war. “It is a cruel and bitter truth that in the fog of war generally, and in our fight against terrorists specifically, that mistakes, sometimes deadly mistakes, occur,” he said.

Obama spoke briefly about the lives Weinstein and Lo Porto had led as aid workers, mentioning that at the time of his capture, Weinstein had been a contractor with the U.S. Agency for International Development in Pakistan. Weinstein was taken hostage by al Qaeda in 2011, and Lo Porto had been held since 2012, the White House said, calling their deaths "uniquely tragic" and adding that Obama "takes full responsibility for these operations."