According to Police, the 65-year-old was in a critical condition and a man had been taken to Wangaratta police station for questioning.
Prime minister Anthony Albanese said Haines was allegedly “attacked” outside her electorate office in Murphy Street, Wangaratta, in northern Victoria.
A major police investigation is under way into the incident on Monday afternoon, with Victoria police, the Australian federal police, Asio and counter terrorism investigators involved.
Police said a 43-year-old man from Tarrawingee was allegedly involved in the incident.