MOSCOW, March 22. /TASS/. Belgian capital Brussels on Tuesday morning was in fact paralyzed after a spate of explosions at the local airport and a metro station. The airport was promptly shut down, all flights were canceled, public transport suspended and schools and child-care centers closed. The Belgian authorities declared the highest level of terrorist alert.

According to preliminary estimates 34 were killed and 135 injured.

Many countries hurried to take their own precautions. World leaders were unanimous in expressing condolences to the Belgian people and in their condemnation of the attacks. Many stressed the need for presenting a common front against terror.

Germany tightened security at its biggest Frankfurt-am-Main airport. About 2,500 police are on duty.

Polish airports have introduced extra security procedures. Board guard patrols have been reinforced in both passenger lounges and staff only rooms.

Austrian police have built up presence at all crowded sites, on transport and at Vienna’s Schwechat airport.

In Russia, sufficient security measures have been taken, a source in the emergency services has told TASS.

"At the moment all passengers undergo thorough checks at railway stations and airports," the source said when asked about the possibility of tighter security measures in the wake of Brussels terror acts.

Police in Sweden told TASS they were building up presence at airports and a number of other transport facilities and closely monitoring the situation.

Spanish Interior Ministry within hours will consider whether it should raise the level of terrorist alert, acting Interior Minister Jorge Fernandez Diaz said. Earlier, the Interior Ministry told TASS Spain preserved level four alert (the last but one highest).

Russian President Vladimir Putin expressed condolences to King Philippe, of Belgians. Presidential spokesman Dmitry Peskov said Putin "strongly condemned the barbaric crimes."

The Russian Foreign Ministry has urged the world community to rally closer together in the struggle against international terrorism. "The issue of global international cooperation on the anti-terrorist track is more crucial than ever before," Russian Foreign Ministry spokeswoman Maria Zakharova said on Life News TV. "The delusion there are countries, cities and corners of the world terrorism will never reach should go never to return. There are no such places or such countries."

The Council of Europe’s Thorbjorn Jagland said the attacks in Brussels were an encroachment on European values.

British Prime Minister David Cameron said on his Twitter page, "I am shocked and concerned by the events in Brussels. We will do everything we can to help."

"This is a blow on the whole of Europe," said President Francois Mitterrand, of France. In his opinion the EU countries must take the necessary measures to ward off the terrorist threat.

"We are in a state of war. All forces are to be mobilized in the face of this threat," said French Prime Minister Manuel Valls.

The German Cabinet’s spokesman Steffen Seibert on behalf of the federal government and Chancellor Angela Merkel expressed solidarity with those affected and voiced the determination to resist the terrorists.

"Germany is mourning together with the people of Belgium. Terrorism will not make Europe give up the values of humanism, openness and freedom," said Germany’s Vice Chancellor Sigmar Gabriel.

Bulgaria strongly condemns the Brussels blasts, said its President Rosen Plevneliyev in a message to King Phillipe.

"Bulgaria strongly condemns these acts of violence. Such actions targeted against civilians cannot be excused. At this dramatic moment I would like to express compassion and sympathy and wish early recovery to survivors," Plevneliyev said.

Polish President Donald Tusk said he was in the stake of shock after the explosions in the Belgian capital. In a statement circulated in Brussels Tusk, the president of the European Council, offered condolences to the relatives and dear ones of all victims.

Austria’s President Heinz Fischer strongly condemned the Brussels attacks. In a special statement he pointed out that terrorism and attacks against civilians should by no means cause deviations from the democratic track. Fischer expressed condolences to the victims and relatives. Austria’s chancellor and vice chancellor slammed the attacks as "cowardly and barbaric."

The Syrian opposition, represented at the peace talks in Geneva by the High Negotiations Committee, responded to the news of terror attacks in the heart of Europe with words of strong condemnation. Its representative, Salem al-Muslad, said he, his colleague and all Syrian people were in deep sorrow and expressed solidarity with the people of Belgium.

The international football federation FIFA told TASS it found the Brussels blasts shocking.

"The Council of Rabbis of Europe is praying for those killed and injured in the Brussels terrorist attacks," its president Pinchas Goldschmidt, the chief rabbi of Moscow, said in a news release.

"We are praying together with the families of those killed and injured in Brussels this morning," the statement runs. Rabbi Goldschmidt expressed condolences to all those affected.

The reaction from Russia’s Civic Chamber was as follows: "Only collective efforts by all countries of the world will be able to cope with this terrible threat and protect civilians. We were deeply aggrieved to learn about the terrorist attacks that hit the airport and metro in Brussels, claiming at least several dozen lives. Our sincere condolences to the families of those killed and injured," the Civic Chamber’s deputy secretary Sergey Ordzhonikidze said in a statement.