Belgian police have sealed off part of Brussels following reports of “one or several armed men”, according to local media.
The men may be holed up in a building on Rue Jean-Baptiste Vanpe in the neighbourhood of Forest, with armed police officers seen hiding behind buildings and staking out a rooftop.
A police helicopter has also been sighted flying overhead.
One of the suspects in the deadly Paris attacks in November 2015, Salah Abdeslam, hid in Forest after the atrocity and was caught up in a shootout with police in a nearby apartment.
There was no immediate indication that Thursday’s incident is terror-related.