BRUSSELS, March 22 -- The latest attacks at Brussels airport and a metro station mark another low by terrorists, European Council President Donald Tusk said on Tuesday, following the explosions which caused at least 13 death in the morning.

"I am appalled by the bombings this morning at Zavantem airport and the European district in Brussels which have cost several innocent lives and injured many others," Tusk said in a statement.

"I extend my sincerest sympathies to the relatives and friends of the victims, he said. "These attacks mark another low by the terrorists in the service of hatred and violence."

"The European institutions are hosted in Brussels thanks to the generosity of Belgium's government and its people. The European Union returns this solidarity now and will fulfill its role to help Brussels, Belgium and Europe as a whole counter the terror threat which we are all facing," he added.

Two explosions were heard shortly before 8 a.m. local time (0700 GMT). The airport's departure hall was damaged heavily, one witness told Xinhua.

The explosion at Brussels airport was a suicide attack, officials confirmed.

Another explosion was later reported at Maelbeek metro station which is within hundred meters from the European Union complex.

At least 13 people were reportedly killed and 35 were wounded. The threat level in Brussels was raised from 3 to maximum 4.