Three people have been injured in Brussels after they were attacked by a woman with a knife on a bus, according to reports from the Belgian capital. 

Local media reported that police shot her in the arm as she tried to escape. The victims are not believed to be in a serious condition.

Public broadcaster RTBF said the incident appeared not to be an act of terrorism. It said the woman, who is thought to be in her 50s, had mental health issues. 

Belgian police have been on high alert since the Islamic State claimed responsibility for the coordinated Brussels bombings that killed 32 people in March. 

An investigation is underway.