President Barack Obama took “full responsibility” for the death of two hostages held by al-Qaeda in a drone strike in January.

Speaking at the White House on Thursday, Obama said that Dr. Warren Weinstein, an American held since 2011, and Giovanni Lo Porto, an Italian national held since 2012, were killed in a counter-terrorism operation on an al-Qaeda compound in the border region of Afghanistan and Pakistan.

“It’s a cruel and bitter truth that in times of war mistakes, sometimes deadly mistakes, can occur,” he said. “I offer our deepest apologies to the families.”

Weinstein’s family issued a statement on a website called Bring Warren Home, noting their disappointment

“We do not yet fully understand all of the facts surrounding Warren’s death but we do understand that the U.S. government will be conducting an independent investigation of the circumstances,” they wrote. “We look forward to the results of that investigation. But those who took Warren captive over three years ago bear ultimate responsibility.”

The White House said the same strike is believed to have killed Ahmed Farouq, an al-Qaeda who held American citizenship. Another U.S. strike in January killed American al-Qaeda member Adam Gadahn, Earnest revealed.

“While both Farouq and Gadahn were al-Qaeda members, neither was specifically targeted, and we did not have information indicating their presence at the sites of these operations,” White House spokesman Josh Earnest said.

As of Thursday morning, Gadahn was still listed on the FBI’s “Most Wanted Terrorists” list.

In 2011, a U.S. drone strike targeted and killed Anwar al-Awlaki, a leader of Al-Qaeda in the Arabian Peninsula, a case that stirred vigorous debate in the U.S. over the killings of Americans fighting alongside terrorist groups without trial.

In his brief statement to reporters, Obama said that after reviewing “hundreds of hours of surveillance, we believed that this was an al-Qaeda compound, that no civilians were present and capturing these terrorists was not possible.”

He added that he has ordered the operations to be declassified so that they could be publicly reviewed.

He also praised the two men, noting they had traveled to Pakistan as aid workers to help those facing poverty.

“There could be no starker contrast between these two selfless men and their al Qaeda captors,” he said.

Get The Brief. Sign up to receive the top stories you need to know right now. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.