American victim in Brussels had encountered terror attack before

Several U.S. residents remain in a Brussels hospital recovering from injuries.

In all, officials say at least 250 people were injured in Tuesday's terrorist attacks, including three Mormon missionaries from Utah: Mason Wells, Richard Norby, who suffered a reported injury to his leg, and Joseph Empey.

Wells' family said he's been treated for burns and shrapnel injuries, reports CBS News correspondent Vladimir Duthiers. Incredibly, this is not the first time Wells has seen terrorism first hand. He was standing near the finish line three years ago when terrorists detonated explosives at the Boston Marathon. Wells was also in France, but not in Paris, when those terrorist attacks occurred in November.

Empey's parents said their son has second-degree burns to his hands and face and shrapnel injuries to his legs.

"We love him a lot and we're just excited to see him again and hope that he gets all the way better," his father said.

Of all the images of carnage in Brussels, perhaps none is more striking than one of 37-year-old Sebastien Bellin, lying in a pool of blood at the airport.

"We were woken up at four o'clock in the morning by friends who had seen the picture. ... I knew when that picture had been taken, he was alive, but then you wonder, you see all this blood and you say, 'Is he going to make it?'" Bellin's father, Jean, said.

After calling several hospitals in Brussels, Jean was able to speak with his injured son.

"I think he was speaking very weakly and very slowly because he was in shock," Jean said. "He saw people dead and people dying, so I'm sure that will stay with him for the rest of his life."

Bellin played for two NCAA teams in the U.S., and was a star center for a pro basketball team in Belgium. He was headed home to Michigan where he lives with his wife and children.

"I want to tell him how proud he should be about his determination, about his courage," Jean said, choking up.

The State Department said it does not know of any Americans killed in the Brussels attack, but several Americans are reportedly still unaccounted for, including a brother and sister from New York.

Family members say they were on the phone with them, heard an explosion and got cut off. The siblings haven't been heard from since. A couple from Kentucky is also reported missing.