Hall of Fame basketball player Dikembe Mutombo was at the airport in Brussels during the series of deadly terrorist attacks Tuesday against the Belgian capital but said he is safe and unharmed.
Mutombo posted two messages and photos on his Facebook page, saying, "I am safe here" and "I am fine."
His charitable foundation also posted a message on Facebook, saying that the former NBA star "was thankfully unharmed."
Multiple explosions rocked the Zaventem international airport and the Brussels subway system, killing at least 34 people. The Islamic State group claimed responsibility for the attacks, saying in a posting from the group's Amaq news agency that its extremists opened fire in the airport and "several of them" detonated suicide belts.
Mutombo, 49, was an eight-time All-Star during his 19-year NBA career and was inducted into the Naismith Basketball Hall of Fame last year.
He was in Brussels waiting for a connecting flight to the United States after visiting one of his foundation's hospitals in his native Congo.
"I was in lounge and next time I heard people start screaming and everyone start running," he told CNN. "Because I was napping, and I was like, 'What's going on?' I thought it was such a joke.
A lady was like, 'Everybody out. Everybody out. We have to go, we have to go. A lot of people are bleeding downstairs and a lot of people are hurt.'
"And there was no hesitation from there. I brought my bag and I start running."
Mutombo told CNN that he ran through the terminal and toward the tarmac.
"I just feel bad for the family of the loved ones that lost their lives," he said. "Feel bad for all the mom and all the citizen that was there that couldn't run and that couldn't move. It was very crazy; I feel very bad. So many mom were trying to push their two kids and three kids. You have one thousand people and everyone running. It was very, very sad."
Belgium's national soccer team responded to the attacks by canceling its scheduled practice session Tuesday.
The Royal Belgian Football Federation posted an announcement on the Twitter account for its national team, saying, "Football is not important today" and that "our thoughts are with the victims."
#tousensemble, our thoughts are with the victims. Football is not important today. Training cancelled.
— BelgianRedDevils (@BelRedDevils) March 22, 2016
On Wednesday, Belgium announced that next week's friendly against Portugal in Brussels has been relocated to Leiria following Tuesday's deadly explosions. Belgium was due to host Portugal at Brussels' King Baudouin Stadium March 29, but city authorities asked the Belgian FA (KBVB) to call off the match following the bomb attacks.
The KBVB had initially said on Wednesday morning that the game would not take place but later announced that an agreement had been reached to play the game in Portugal. The game had been scheduled as a warm-up for both teams ahead of this year's European Championship in France.
President Barack Obama was asked by ESPN's Karl Ravech during the Rays-Cuba baseball game to address the nation about the attacks.
"I had a chance to talk to the Belgian prime minister earlier this morning, right after the explosion had happened, and this is just one more example of why the entire world has to unite against these terrorists -- that the notion that any political agenda would justify the killing of innocent people like this is something that's beyond the pale," Obama said. "We are going to continue with the over 60 nations that are pounding ISIL and are going to go after them. ... In the meantime, obviously, our thoughts and prayers with those who were lost and hoping for a speedy recovery to those who've been injured."
French Interior Minister Bernard Cazeneuve said the explosions are a reminder that a "very high security level" will be required during the European Championship. He said the measures taken to guarantee "collective security" at the June 10-July 10 tournament will include the mobilization of specially trained emergency staff, police forces and firefighters.
The two airport blasts, at least one of them blamed on a suicide bomber, left behind a chaotic scene of splattered blood in the departure lounge as windows were blown out, ceilings collapsed and as travelers streamed out of the smoky building.
About an hour later, another bomb exploded on a rush-hour subway train near the European Union headquarters. Terrified passengers had to evacuate the train through darkened tunnels to safety.
"What we feared has happened," Belgian Prime Minister Charles Michel said. "In this time of tragedy, this black moment for our country, I appeal to everyone to remain calm but also to show solidarity."
Belgium raised its terror alert to the highest level, diverting planes and trains and ordering people to stay where they were for most of the workday.
Sebastien Bellin, a European professional basketball player who played collegiately in the United States, was injured in one of the airport explosions, according to his former team in Belgium.
One international soccer player was at the Zaventem airport when the explosions were reported. Norwich forward Dieumerci Mbokani, who is from Congo, was "unharmed but shaken by the tragic events," the English club said in a statement.
Mbokani was visiting family in Brussels, where he played for Anderlecht for two seasons until 2013.
Belgian golfer Thomas Pieters lives in Antwerp, Belgium, and is playing at the WGC-Dell Match Play Championship in Austin, Texas.
"I woke up at 6 a.m. and my phone was just buzzing,'' Pieters said during a news conference Tuesday. "Everybody was asking me, 'Is your family OK?' And I kind of knew what was going on, so I opened the news sites and it was just one of the worst days to wake up.
"Even when it happened in Paris, it's close, but it's not right near your people. And now it happens to somewhere I go almost every time I fly out. That's where I go. It's shocking to see so many images and the videos. It's a sad day.''
Chad Wells, the father of a Utah Mormon missionary seriously wounded in the airport blast, told the Associated Press that his son is recovering from severe burns and a severed Achilles tendon. Wells said he and his son were only a block from the Boston Marathon bombing in 2013. They went to watch his wife run the race. None of them was injured, but they felt the ground shake. The younger Wells also was two hours away from Paris during the series of attacks in the city last November.
The explosions in Belgium occurred four days after Salah Abdeslam, a prime suspect in those Nov. 13 Paris attacks that killed 130 people, was arrested in Brussels.
ESPN FC, ABC News, ESPN's Bob Harig and The Associated Press contributed to this report.