A female magistrate and a court clerk have been shot dead in a courtroom in the Belgian capital.
A lone gunman opened fire in a building near the main Palais de Justice in Brussels at about 1115 (0915 GMT).
Belgian media identified the dead justice of the peace as Isabelle Brandon and clerk Andre Bellemans, who were presiding over a civil tribunal.
A search is under way for the gunman - who was reported to be injured - after he fled the scene on foot.
Officials said the attacker had attended a morning session, but no immediate details were given about his identity or possible motive.
"He was present at the outset of the hearing," said Jean-Marc Meilleur of the Brussels prosecutor's office.
"Toward the end of the session, he pulled a gun. Shots were fired, after which the killer fled."
Police have sealed off surrounding streets, and issued warnings to shoppers and tourists to go indoors.
Justice Minister Stefaan De Clerck said this was the first time in Belgian judicial history that a magistrate has been killed in the middle of a court hearing, state broadcaster RTBF reported.
He said that security would be stepped up, but not to expect closed rooms and CCTV everywhere, as "justice should be about proximity to people".
Lawyers and judges have held a minute's silence for the victims in front of the Palais de Justice.
A lawyer who works at the court, Pierre Brimeyer, told AP: "We have been witnessing increasing levels of violence and tension in the Palais de Justice for years.
"Incidents have happened before and now we have reached a critical level."