BLOOD BROTHERS: Siblings ID'd as Brussels airport, subway suicide bombers; 1 arrest made as manhunt for ISIS Bomber No. 3 goes on

Belgian police continued their dragnet Wednesday for the mystery man who appeared with two suicide bombers in a surveillance photo taken a day earlier, moments before explosions ripped through Zaventem Airport, killing at least 11 in the first of twin attacks that shook Brussels.

Oveight, police in Brussels executed several raids and made an arrest in coection with the terror attacks, but later dismissed reports that it was the man seen in the photo with the two bombers. That unidentified man appeared in the photo wearing a possible disguise and walking abreast of two men pushing carts suspected to be loaded with suitcase bombs.

"This third unidentified person has been on the run for awhile now."

- Frederic Van Leuw, Belgian prosecutor

A Belgian official said Wednesday moing the suspect in custody is neither the man in the photo nor wanted bomb maker Najim Laachraoui, who is suspected of equipping the terrorist who struck in Paris in November and may have played a role in Tuesday's bombings.

The third suspect in the surveillance photo "left a bag and his bag contained the most important explosive charge," Belgian federal prosecutor Frederic Van Leuw said at a Wednesday news conference. "His bag exploded right after the arrival of federal police. Fortunately no one was hurt.

"This third unidentified person has been on the run for awhile now," Van Leeuw said.

The uamed suspect was arrested in Brussels' Anderlecht district, adjacent to the Molenbeek district that has become synonymous with homegrown jihadism in Belgium. Raids were expected to continue throughout Belgium Wednesday, as Laachraoui apparently remained on the loose.

Laachraoui is thought to have built the suicide vests used by the attackers Tuesday and the terrorists who killed 130 people in Paris on Nov. 13, according to a police official who told The Associated Press that Laachraoui's DNA was found on all of the devices and in a Brussels apartment where they were made.

Police searched an apartment Tuesday where numerous chemicals and bomb-making materials were found, but it was not clear if this was Laachraoui's bomb factory.

Earlier, two men suspected of taking part in the bombings were identified as Khalid and Ibrahim El-Bakraoui.

Khalid is believed to have blown himself up on the Metro, an attack which killed at least 20 and injured more than 100, while Ibrahim is believed to be one of the airport bombers. The fourth bomber, the man in the far left of the airport photo pushing a cart next to Ibrahim, has not yet been identified.

The twin attacks, for which ISIS has claimed credit, shook the European Union capital and left at least 31 people dead and at least 270 injured.

The brothers were well-known to police. In a raid Tuesday at Ibrahim's address, a Belgian prosecutor said "there was a paper where he described that he is insecure, that he is lost and he does not know what to do and he might end up in jail."

"I don't know what to do. I'm looked for everywhere and I might even find myself in a jail cell," a portion of the letter, read by Van Leeuw, said.

Both Ibrahim and his brother were Belgian citizens and bo in Brussels, authorities said.

Belgian media reported that Khalid, 27, rented an apartment in the Forest section of the city that was raided by authorities March 15. During that raid, a police sniper killed a man identified as Mohamed Belkaid, 35, an Algerian with links to ISIS.

The March 15 raid led to Friday's arrest of Paris attack suspect Salah Abdeslam after one of his fingerprints was discovered in the apartment. Politico Europe, citing a senior Belgian official, reported that Abdeslam was supposed to take part in Tuesday's attacks. The report did not specify what role Abdeslam would have played.

Over the weekend, Belgium's Foreign Minister disclosed that Abdeslam had been preparing further attacks, saying the suspect was "ready to restart something from Brussels."

The Guardian also reported that one of the El-Bakraoui brothers had rented a safe house in Charleroi, Belgium that was used by Paris attackers Abdelhamid Abaaoud and Bilal Hadfi as a rendezvous point prior to the assaults that killed 130 people in the French capital. The paper also reported that one of the brothers had provided weapons and ammunition to the terrorists who attacked the Bataclan concert hall on that deadly night.

DH reported that in October 2010, Ibrahim, 30, was convicted of shooting at police with a Kalashnikov during an attempted robbery. He was sentenced to nine years in prison. In February 2011, the paper reported, Khalid was sentenced to five years' probation in coection with a string of carjackings.

Van Leeuw said that while both brothers had "heavy rapsheets," all arrests were seemingly unrelated to terrorism.

The Associated Press contributed to this report.