BRUSSELS — Attackers detonated bombs at the airport and on a metro train beneath the European Union’s capital today, killing at least 26 people and confirming the worst fears of European officials, who proclaimed the continent at war.

Two explosions, at least one likely caused by a suicide bomber, hit the departures area of Brussels’ Zaventem airport during the busy morning rush, collapsing the ceiling and sending panicked travelers rushing for cover. Belgian Health Minister Maggie de Block told Belgian media that 11 people were killed and 81 injured.

An hour later, another 15 people were killed and 55 injured in an explosion on a subway train not far from the headquarters of the European Union, a spokesman for the Brussels Metro said.

“What we feared has happened,” Belgian Prime Minister Charles Michel told reporters. “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. Airports across Europe immediately tightened security.

“We are at war,” French Prime Minister Manuel Valls said after a crisis meeting called by the French president. “We have been subjected for the last few months in Europe to acts of war.”

European security officials have been bracing for an attack for weeks, and warned that the Islamic State group was actively preparing to strike. The arrest Friday of a key suspect in the November attacks in Paris heightened those fears, as investigators said more people were involved than originally thought, and some are still on the loose.

There was no immediate claim of responsibility for today’s attacks, and Michel said there was no immediate evidence linking key Paris suspect Salah Abdeslam to them. After his arrest Friday, Abdeslam told authorities he had created a new network and was planning new attacks.

At the airport, explosions splattered blood across the departure lounge; smoke was seen billowing out of the terminal.

Anthony Deloos, an airport worker for Swissport, which handles check-in and baggage services, said the first explosion took place near the Swissport counters where customers pay for overweight baggage. He and a colleague said the second blast hit near the Starbucks cafe.

“We heard a big explosion. It’s like when you’re in a party and suddenly your hearing goes out, from like a big noise,” Deloos said, adding that shredded paper floated through the air as a colleague told him to run.

“I jumped into a luggage chute to be safe,” he said.

Tom De Doncker, 21, check-in agent intern, was near the site of the second explosion. “I saw a soldier pulling away a body,” he said. “It felt like I was hit too” from the concussion of the blast.

Zach Mouzoun, who arrived on a flight from Geneva about 10 minutes before the first blast, told BFM television that the second, louder explosion brought down ceilings and ruptured pipes, mixing water with victims’ blood. “It was atrocious. The ceilings collapsed,” he said. “There was blood everywhere, injured people, bags everywhere. We were walking in the debris. It was a war scene.”

Near the entrance to Brussels’ Maelbeek subway station, not far from the headquarters of the European Union, rescue workers set up a makeshift medical treatment center in a pub. Dazed and shocked morning commuters streamed from the metro entrances.

“The metro was leaving Maelbeek station for Schuman when there was a really loud explosion,” said Alexandre Brans, 32, wiping blood from his face. “It was panic everywhere. There were a lot of people in the metro.”

Francoise Ledune, a spokeswoman for the Brussels Metro, said on BFM television there appeared to have been one explosion on the subway in a car that was stopped at Maelbeek.

Spokesman Guy Sablon said 15 were killed and 55 injured in that attack.