Police subdued a knife-wielding man with a Taser stun gun after he attacked a worker at a medical centre and held another hostage.
Armed police officers were called to the Summerfold Medical Centre in Burgess Hill, West Sussex on Monday.
Police said a man, who cut one staff member, had to be shot with the Taser gun after negotiations for almost five hours failed.
Sussex Police said a 39-year-old local man was being questioned.
A spokesman said the hostage was extremely shaken following the ordeal at the centre on Leylands Road but was not injured.
Deputy Chief Constable Geoff Williams said a cordon was put in place during the incident.
Sussex Ambulance and West Sussex Fire and Rescue Service also attended the scene.