Brussels on highest alert of 'imminent threat' after Paris attacks

BRUSSELS -- Belgium's capital city is on a level four alert, the highest, after the government warning that terrorists are poised to strike as they did in Paris.

A man suspected in the attacks on Paris is believed to be on Belgian soil. If he is not found and if the alert is still high on Monday, school in Brussels will be closed.

In the meantime, for the first time, we're hearing from the American band on stage during the massacre at the concert hall in Paris.

Rock band the Eagles of Death Metal is telling its survival story for the first time since terrorists burst into the Bataclan concert hall during their set. "People were playing dead and they were so scared. So many people wouldn't leave their friends and so many people put themselves in front of people," lead singer Jesse Hughes said in an upcoming exclusive interview with Vice News.

"Several people hid in our dressing room and the killers were able to get in and killed every one of them, except for a kid who was hiding under my leather jacket," Hughes said.

No band members were harmed but touring staff member Nick Alexander was shot and killed.

ABC News learned that Salah Abdesalem, the only attacker not to die in the city-wide siege, passed through multiple checkpoints in the days after the attacks.

He was picked up by two friends whom he begged to take him to Brussels. The attorney for one of them told ABC News that Abdesalem was picked up shortly after the attacks ended.

On the drive to Brussels, the two friends say they noticed what may have been a suicide vest hidden beneath a large coat but managed to breeze through three separate police checkpoints.

When they arrived, Abdesalem told other friends he was terrified of ISIS retribution because he didn't blow himself up like most of the Paris attackers.

One of the attackers, Abdesalem's younger brother Brahim, detonated his vest outside the Stad du France during a France Germany friendly match, which was heard by players.

The French defense ministry says the only way to defeat ISIS is with boots on the ground. He added the French aircraft carrier will arrive off the coast of Syria on Monday.

This means we could see both U.S. and French troops fighting ISIS.

PHOTOS: Victims of Paris terror attacks

In France, meanwhile, police issued a new appeal to identify the third attacker who was killed in the attacks at the national stadium in Paris. They posted a photo of the man on Twitter, appealing to the public for information that would help identify him.

Western leaders stepped up the rhetoric against the Islamic State group, which has claimed responsibility for the attacks in Paris that killed 130 people and wounded hundreds more; the suicide bombings in Beirut that killed 43 people and injured more than 200; and the downing of the Russian airline carrying 224 people in Sinai. All happened within the past month.

Speaking from Kuala Lumpur, President Barack Obama said the world would not accept the extremists' attacks on civilians as the "new normal," and vowed the United States and its international partners would not relent in the fight against the Islamic militants.

French Defense Minister Jean-Yves Le Drian said IS must be destroyed at all costs.

"We must annihilate Islamic State worldwide ... and we must destroy Islamic State on its own territory," Le Drian said. "That's the only possible direction."

France has intensified its aerial bombing in Syria and Le Drian said French aircraft carrier Charles de Gaulle, which has been sent to help operations against IS militants in Syria, will be "operational" from Monday and "ready to act."

French President Francois Hollande is scheduled to meet in Paris with British Prime Minister David Cameron on Monday, and will travel to Washington and Moscow later in the week to push for a stronger international coalition against IS. Cameron is expected to outline his plan for combating the Islamic militants this week as he seeks Parliamentary approval to join France, the United States and Russia in striking the group's strongholds in Syria.

For full coverage on the Paris terror attacks, click here.

The Associated Press contributed to this report.