A hunt for suspects is underway in Brussels after a terrorist attack in the Belgian capital early Tuesday morning. 

Explosions ripped through the airport and subway system, killing at least 30 and injuring about 230 more.      

The attacks have sparked widespread condemnation around the world, and heightened security, including in Canada.

“With the security level that they've established, it's the highest level and so they've literally ordered people to stay put,” said Seth Montgomery, a Maritimer living in Belgium.

Security has been tightened at subways stations in Toronto and Montreal, and airports in those cities are closely monitoring the situation.

Via Rail in Halifax says it's keeping an eye on developments, as well. In a statement, the railway says there've been no specific threats, but security and vigilance are being reinforced, a sentiment echoed by the Government of Canada.

"Stay alert, stay vigilant. Be aware of your circumstances and your surroundings," said Minister of Public Safety Ralph Goodale.

Investigators have already found a nail bomb and an ISIS flag in a nearby home. The Government of Brussels has invited people to observe a moment of silence on Wednesday.

Some countries have already payed tribute to the victims, bathing national monuments in the colours of the Belgian flag.

With files from CTV Atlantic’s Bruce Frisko.