PARIS– UPDATE: A suspect in the Brussels attacks which killed at least 31 people at Brussels’ airport and subway on Tuesday has been arrested by authorities. The suspect has not yet been identified. Belgian media previously reported the suspect was Najim Laachroui, but the AFP has just revealed Laachroui was identified as one of the two suicide bombers at the airport thanks to DNA evidence.

The second suicide bomber at the airport has been identified as Ibrahim el-Bakraoui.

El-Bakraoui’s brother, Khalid, is suspected to be the suicide bomber of the subway blast.

Authorities are still seeking the third man seen on airport surveillance camera with Najim Laachroui and Ibrahim el-Bakraoui. The man, wearing a black hat and a light jacket, left a bag containing explosives before leaving the airport. He’s currently on the run, as is another suspect, Mohamed Abrini.

Laachroui was suspected to be the group’s supplier of ammunitions and explosive vests for the Belgium and Paris attacks which killed 130 people. His DNA was found on all but one of the explosive vests used on Nov. 13. ISIS has claimed both attacks.

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All four men – the el-Bakraoui brothers, Abrini and Laachroui — belong to the same terror cell as Salah Abdeslam, one of Paris attacks’s ringleaders who was arrested five days ago in Brussels.

Brussels was hit on Tuesday by two coordinated blasts — one in its subway and another one at its airport. At least 200 people were injured. It was the deadliest attack in Belgium, France’s neighboring country, since World War II.

Abdeslam, captured five days ago in Brussels, is currently being held in a prison in Bruges and has reportedly said he was willing to cooperate. Explosives were found in his appartment, leading investigators to suspect he was plotting another attack.

Belgian authorities have declared three days of mourning. Trains, subways have partially reopened in Brussels, which remains on maximal alert. Belgium’s biggest multiplex chain, Kinepolis, remains closed. Special forces have been deployed throughout the city.

More to come.