BRUSSELS (AP) — Belgian authorities raised the terror alert to its highest level in the capital late Monday after the fatal shooting of two Swedes in Brussels that Prime Minister Alexander De Croo linked to terrorism. The gunman remained at large.

The killings happened some 3 miles (5 kilometers) from a stadium where over 35,000 fans were watching a Belgium-Sweden soccer match, Belgium’s anti-terror center said. The match was abandoned halfway through.

“The population needs to be actively vigilant and avoid any unnecessary travel,” anti-terror center spokeswoman Laura Demullier said, adding that the top priority for authorities was to get the thousands of fans safely out of the King Baudouin Stadium.

The center also said that the terror alert for the rest of the country was raised to its second-highest level. Raising the terror level in the capital to the top 4 rating means that a “threat is extremely serious.” It previously stood at 2, which means the threat was average.

“I have just offered my sincere condolences to @SwedishPM following tonight’s harrowing attack on Swedish citizens in Brussels,” De Croo said. He added on X, formerly known as Twitter, “As close partners the fight against terrorism is a joint one.”

It was not immediately clear if the shooting was linked to the international uproar over the Israel-Hamas war.

“A horrible shooting in Brussels, and the perpetrator is actively being tracked down,” said Interior Minister Annelies Verlinden, adding that she was joining government talks at the National Crisis Center.

Media reports aired amateur videos showing a man shooting several times near a station using a large weapon.

A police official, who spoke on condition of anonymity because they were not authorized to speak to reporters, said the two victims were Swedes.

Police spokeswoman Ilse Vande Keere said officers arrived soon at the scene, and sealed off the immediate neighborhood. She declined to elaborate on circumstances of the shooting.

The shooting came at a time of increased vigilance linked to the ongoing Israel-Hamas war that has heightened tension in several European nations. At the same time, the Belgian capital has been the scene of increased violence linked to increasing international drug trafficking.

Sweden raised its terror alert to the second-highest level in August after a series of public Quran-burnings by an Iraqi refugee living in Sweden resulted in threats from Islamic militant groups.