At least two Americans are among the dead from the twin terror attacks in Brussels earlier this week, a senior U.S. official told Fox News on Friday.

Two siblings flying to New York. A Peruvian chef. A Belgian law student.

These are some of the dead and missing in Tuesday's terror attacks in Brussels.

EU ministers gather in Brussels to discuss policy in wake of deadly bombings.

The terrorists responsible for the attack in Brussels may have also been considering an assault on a nuclear power plant.

After the Paris terror attacks in November, Belgian authorities reportedly discovered 12 hours of footage indicating that Islamic State adherents were spying on a senior official with Belgium’s nuclear power program, according to Derniere Heure, a French-language newspaper based in Brussels.

At least one of the Brussels suicide bombers, suspected of being a terrorist, was deported by Turkey less than a year ago, but Belgian officials said neither brother involved in the attacks had been under suspicion until recently.

Five terrorists -- three dead, two whose fates are unknown.

So far, that's how many people that authorities say played a part in Tuesday's terror attacks in Brussels, Belgium, that killed 31 people and injured 270.

Investigators also accumulated evidence that the same jihadist network was involved in the deadly Paris attacks last November.

A second terrorist took part in the subway bombing Tuesday in Brussels and authorities believe he may have survived the blast, meaning there are potentially two "mystery bombers" from the twin attacks on the run, according to reports.

The police had been searching for the Bakraoui brothers since the March 15 raid in Brussels, Belgian officials said. A third attacker has not been publicly identified, and is still at large.

Belgian authorities were chasing the key suspect in the worst terror attack in Belgium’s history.

Four men on Tuesday attacked a Brussels airport and train station, killing 32 people and injuring around 260 others. Several Belgian media news outlets reported early Wednesday that Najim Laachraoui, who they identified as one of the suspected attackers at the airport, was detained in Brussels. Belgian prosecutor Eric Van der Sypt denied this.