A series of bomb explosions shook Brussels Tuesday morning over a span of 80-plus minutes, leaving at least 31 dead and sending the region into a state of high alert.

The death count is likely to rise, authorities cautioned. Another 187 or more have been injured.

Details are still emerging, but the latest reports revealed that among the injured were three Mormons from Utah, visiting the Brussels area for missionary work.

The Church of Jesus Christ of Latter-day Saints issued a statement identifying them as 66-year-old Richard Norby of Lehi, 20-year-old Joseph Empey of Santa Clara and 19-year-old Mason Wells of Sandy.

A U.S. official told CBS News correspondent David Martin an American military family was also among the injured.

In a statement, the Department of Defense said: “One U.S. service member and his family who were caught up in this tragedy. Due to privacy concerns, we are not releasing the status of their injuries at this time.”

Defense Department and U.S. Embassy officials tell CBS News they expect the number of American casualties in Brussels will go higher because there are many Americans who work in Brussels.

“All @Eurostar trains to #Brussels suspended after attacks at airport and metro,” BBC tweeted.

Fox News reported shots were fired at the airport by an individual who shouted in Arabic, then an explosion rocked the facility.

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Brussels has raised the terror alert to its highest level; London is on high alert, as well as Paris.

The airport in Brussels was in shambles from a terror attack.

The airport in Brussels was in shambles from a terror attack.

The latest in the fast-moving story is that more than a dozen were killed and up to 35 injured as two blasts struck Zaventem airport by the American Airlines desk and three more explosions hit at Maalbeek metro station, near the European Union buildings. The second series of blasts occurred roughly 80 minutes after the first, leaving some officials puzzled at the identity of the perpetrators.

“Usually the ISIS, al-Qaida [terror attacks] … are separated by a few minutes. But this is a long time,” said Walid Phares, a Middle East and terrorism expert, during a Fox News interview. “This is why Brussels is on ‘high alert,’ authorities want to make sure the danger is over.”

All public transportation facilities in Brussels have been shut. And British Prime Minister David Cameron called for an emergency meeting of his cabinet officials.

At least three explosive vests have been found at the airport, but it’s not clear who is behind the attacks.

Authorities have officially declared the attacks as terror-related. No group has yet claimed responsibility, and authorities are still trying to determine who may have launched the attacks.

Intelligence officials are focusing their investigation on determining if the blasts were related to the arrest in Brussels of Salah Abdeslam, the leading strategist for last year’s Paris attacks. Abdeslam was arrested just last Friday, and some see a clear tie – that Tuesday’s terror attacks are revenge for his arrest. Regardless, the strikes have put a halt to nearly all normal activities in several communities.

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“They have now struck at the heart of Europe,” one security expert said on Fox News.

And another terror analyst said during a separate interview on Fox News: “The idea that you have synchronized cells, synchronized teams … this is jihadi. You create as much chaos as possible by having synchronized attacks. … Terrorism is fundamentally about the spreading of fear. If you want to spread fear, you want to choose symbolic targets.”

And why Brussels?

“Brussels is the hub of Europe,” he said. “If you want to take the war, the holy war, to the infidel in Europe, Brussels is [the area to target].”

Witnesses said the blasts filled the subway areas with smoke, and blood was everywhere.

One Metro passenger described to BBC what he saw and heard, saying, “There was a loud thud” and “then a lot of dust and smoke.”

Another eyewitness said: “I said run, run” and “my colleague hid in the luggage carousel.”

Authorities in Brussels have warned citizens to “stay where you are,” BBC reported.

The Brussels airport that was hit was the same facility that was used by U.S. senators just this past weekend.

As Bloomberg View reported: “For American officials and experts who traveled through the Brussels airport this past weekend, this was a close call. Whether that will result in a change in how the U.S. thinks about the fight against the Islamic State remains to be seen.”

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