Belgian police have launched a manhunt in a Brussels neighbourhood after at least one gunman opened fire on officers during an anti-terror raid linked to last year's Paris attacks, officials said.
Three police officers were slightly injured during the operation.
Two hours after the first shots were fired, a big swathe of the Forest neighbourhood was in lockdown as special police units in body armour and balaclava hoods moved in, several with their guns drawn.
A helicopter was hovering overhead to patrol the area as police were still hunting for at least one suspect.
"Two individuals apparently barricaded themselves inside a home," Forest mayor Marc-Jean Ghyssels said.
It was not immediately clear if the two people escaped, or whether police were searching for more people.
A police official also said it was not clear if the police officers were struck by bullets or injured in another way.
Another official said that the anti-terror raid in the Forest neighbourhood was linked to the Paris attacks on November 13 that killed 130 people.
The area is close to Molenbeek, home to several people involved in the attacks.
Police sealed off a wide perimeter around the area where the shots were heard to keep the many bystanders at a safe distance. Several hundred spectators were trying to get a closer look at the operation in the multicultural neighbourhood, which has a big Audi car factory nearby. Audi asked its personnel to stay at the plant while the police raid was going on.
Several hooded officers wearing body armour milled around the neighbourhood and ambulances were on standby.
Four months on, Belgian police and magistrates have still been piecing together the role Belgian nationals played in aiding the Paris attackers, as well as trying to track down missing suspects including international fugitive Salah Abdeslam, whose brother Brahim was one of the suicide bombers.
The suspected ringleader of the attacks was a Brussels resident, Abdelhamid Abaaoud. Another attacker, Bilal Hadfi, was said to have lived for a time in the Forest neighbourhood.
Belgian authorities have stepped up their counter-terror efforts since a lone gunman killed four people at the Brussels Jewish museum in May 2014. The small Western European country has also been prime recruiting ground for Islamic State, and officials freely acknowledge their concerns about what radicalised recruits might do after returning home from the battlefields of Syria or Iraq.
Tuesday's raid was a reminder of the anxious days the Belgian capital lived through in November and December, when the subway and schools were closed for a time, and the New Year's Eve fireworks display was cancelled because of the threat of extremist violence.