3rd Brussels Bomber Identified: Officials

Belgian authorities believe they have identified the third suicide bomber in the Brussels attack as Najim Laachraoui, a 24-year-old who has been sought by police since the Paris attacks in November, three Belgian law enforcement officials told ABC News.

The officials said that evidence indicates Laachraoui is the man in dark clothes on the left in a surveillance photo from the Brussels airport showing three of the four alleged Brussels attackers. The man in the middle, identified earlier today as 29-year-old Ibrahim El-Bakraoui, was also a suicide bomber. The man on the right, in the lighter clothes, has yet to be identified and is still on the run, Belgian officials said.

A wanted poster featuring Laachraoui and posted online shortly after the Paris attacks says that Laarchraoui's DNA was found in a rented house in a Brussels suburb and an apartment in central Brussels' Schaerbeek neighborhood - locations a Belgian prosecutor said Monday "was used by the terrorist group" in the Paris attacks. International media reports said that Laarchraoui's DNA was also found on two of the suicide belts used in the November Paris attacks. Officials told ABC News he is suspected of being the terror cell's bombmaker.

Authorities said Laachraoui had left for Syria in 2013 and in September 2015, two months before the Paris attacks, an individual using one of Laarchraoui's aliases was spotted in a car with Paris attacks suspect Salah Abdeslam on the border between Hungary and Austria. Abdeslam was arrested in Belgium Friday.

The Brussels attacks began Tuesday morning when two bombs were detonated at Brussels' Zaventem airport. The next bombing, a little more than an hour later, consisted of an explosion on the rail tracks of the Maelbeek subway station, according to a spokeswoman for Brussels' transportation department. The bomber there was also identified today as Ibrahim El-Bakraoui's brother, Khalid El-Bakraoui.

An ISIS-affiliated website claimed that ISIS "fighters" were responsible for the attacks. A statement on the site says the terror group "carried out a series of bombings with explosive belts and devices" in "the Belgian capital Brussels, a country participating in the international coalition against the Islamic State [ISIS]."

The website's claims have not been independently verified, nor have Belgian authorities made an official statement regarding the terror group's possible involvement in the attacks.

Belgian Ambassador to the U.S. Johan Verbeke told reporters Tuesday that "statements ... cries" in Arabic were reportedly heard at the airport, "so that is the first indication of what the source is maybe, but I don't want to elaborate on that because that is definitely something that has to be further investigated."

Verbeke said he did not know what was allegedly said in Arabic.

During a raid in the Brussels neighborhood of Schaerbeek following the attacks, authorities say police found an "explosive device containing nails," "chemical products" and "an ISIS flag."

The U.S. State Department has issued a travel warning to Americans for all of Europe, citing the threat of "near-term" attacks.

"Terrorist groups continue to plan near-term attacks throughout Europe, targeting sporting events, tourist sites, restaurants, and transportation," the alert said. "U.S. citizens should exercise vigilance when in public places or using mass transportation."

No Americans have yet been counted among the dead, but at least nine were injured in Tuesday's attacks, including three Mormon missionaries, as well as a member of the U.S. Air Force and five of his family members.

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