Justin and Stephanie Shults are the only identified American victims whose identities have been revealed so far

On Friday, the wife of an Air Force lieutenant colonel was also confirmed as one of American victims

Another American has been identified as killed in the attacks in Brussels, bringing the total number of US citizens confirmed as victims to four.

An official confirmed the death Sunday night but was unable to reveal their identity since they 'were not authorized to discuss the matter publicly'.

They added that they did not disclose the victim's identity 'out of respect for the families in this difficult time'.

Officials have said previously that at least a dozen Americans were injured in the attacks last Tuesday.

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The bodies of missing Americans Stephanie and Justin Shults were identified yesterday, five days after the blasts at Brussels airport

Pictured above the aftermath of the bombing at the Brussels Airport

On Friday, the wife of an Air Force lieutenant colonel was also confirmed as one of Americans killed in the Belgium terror attacks Tuesday, officials told Fox News.

The woman's name was not revealed.

Earlier Sunday, the White House said that President Barack Obama had telephoned the parents of an American couple identified as among the dead in the attacks.

The White House said Obama offered his condolences and praised Justin and Stephanie Shults as epitomizing all that was good about America.

Justin Shults was originally from Gatlinburg, Tennessee, and his wife, Stephanie, was a native of Lexington, Kentucky.

They graduated together from Vanderbilt University's Owen Graduate School of Management.

A family member says they were dropping Stephanie's mother off at the Brussels airport and were watching her walk through security when the bombs went off.

The bodies of the Shults' were identified today, five days after the blasts at Brussels airport.

Mr Shults' brother, Levi Sutton, paid tribute to his sibling, who is originally from Tennessee on Twitter saying: 'We found out today that cowards took my brother's life just weeks after his 30th birthday.

The bloody scene at Brussels Airport on Tuesday after two explosions were heard

President Barack Obama has urged Americans not to 'stigmatize' Muslims in the wake of the Brussels terrorist attacks that left 34 dead - including four U.S. citizens.

Victims: Justin Shults was originally from Gatlinburg, Tennessee, and his wife, Stephanie, was a native of Lexington, Kentucky. Pictured together above

'I was blessed to have Justin as a big brother. He was smart and kind and generous. I never met a single person that didn't like him.

'He worked hard his whole life and achieved goals that most could only dream about.

'He traveled the world leaving each destination better than when he arrived.

'Knowing that I'll never be able to see him again hurts but it's worse that my future children will never get to know their uncle Justin as he would've been a great role model. Please pray for my mom.'

The grim news was revealed by company executives at Clarcor, the engineering firm the 30-year-old worked for.

Dutch siblings Sascha and Alexander Pinczowski, pictured left and right, were living in New York and were catching a flight back to the U.S. on Tuesday when the first explosions happened

Dutch siblings who were living in New York have also been confirmed among the dead in the Brussels terror attacks.

The family of Sascha and Alexander Pinczowski have learned that the two were killed in the Tuesday bombing at Brussels Airport.

The siblings were on the phone to their mother in Holland when the first explosions were heard and the line went dead.

Alexander Pinczowski was living in New York with his girlfriend, and his sister Sascha was splitting her time between America and Europe after graduating from Marymount Manhattan College with a degree in business last May.