Europe Updated: Brussels on lockdown after airport and metro attacks By Michelle Baran / March 22, 2016 Share 1 In this image provided by the Belgian Federal Police are three men suspected of taking part in the Brussels airport attack. The man at right is being sought by police and the two others were probably suicide bombers. Photo Credit: Belgian Federal Police/AP -- After explosions at the Brussels Airport and in a subway station near the European Union headquarters killed more than 30 people and injured more than 180 on Tuesday, the Belgian capital went into complete lockdown, news outlets reported.Planes and trains have been diverted from Brussels, the entire subway and public transportation system is shut down, and people have been asked to stay off the streets. The Eurostar and Thalys train services into Brussels were suspended. The airport has been closed at least through Wednesday, the airport's operator said in a tweet.Belgium declared that the country is on its highest terror alert level.On Monday, the U.S. State Department issued a travel alert for all of Europe, "following several terrorist attacks, including the March 22 attacks in Brussels."Brussels is working to get the city back up and running as soon as possible, said Rudi Vervoort, minister-president of the Brussels capital region. He said that Brussels is working with federal authorities to partially reopen the subway. As for surface transportation, the tramway will be reopened as soon as possible, he said.Events that drive large crowds such as cultural or sporting events, as well as popular tourist sites, will only be closed on Tuesday and after that will be open as normal, according to Vervoort. Shopping centers will also be open on Wednesday morning and security measures will be put in place by the companies that manage those centers and by the authorities, he said. “The objective is, of course, to maintain a normal life as soon as this Wednesday, March 23.” The U.S. Embassy in Belgium urged U.S. citizens to monitor events in Belgium and follow the instructions of local authorities. On its Twitter feed, the embassy encouraged all those who were safe to contact friends and family and let them know their whereabouts.The State Department's Europe alert said that U.S. citizens should be cautious when in public places or using mass transportation and exercise particular caution during religious holidays and at large festivals or events. "Terrorist groups continue to plan near-term attacks throughout Europe, targeting sporting events, tourist sites, restaurants and transportation," the alert said.Security was heightened across Europe on Tuesday, with France deploying additional security officers across the country. Airports stepped up security throughout the continent. This report was updated Wednesday, March 23, to include information about the State Department alert and the Brussels airport.