What we know so far: MP fighting for life after attack

* Helen Haines, a 65-year-old mother of three from a farm just outside Wangaratta, has been an independent MP for the Victorian seat of Indi since 2019.

* A former nurse, she is particularly interested in healthcare and anti-corruption measures.

* Indi had been safely held by conservatives until it was won by one of the first grassroots independents, Cathy McGowan, in 2013.

* Dr Haines was returning to her Wangaratta electorate office on Monday when she was struck by a white Toyota LandCruiser about 3.35pm.

* The incident resulted in the MP suffering critical injuries to her lower body.

* She was rammed twice by the four-wheel drive, which did a U-turn before striking her, witnesses said.

* A local barber, Ricky Jefferies, performed a citizen's arrest on the 43-year-old suspect and removed a knife from him.

* The suspect was taken into custody by police and was still being questioned on Tuesday.

* Dr Haines was taken to a local hospital before being airlifted to Melbourne's The Alfred in a critical condition.

* She underwent surgery on Monday night and was in a critical but stable condition on Tuesday morning.

* The Australian Federal Police, Victoria Police and a Joint Counter-Terrorism team are investigating the incident.

* Prime Minister Anthony Albanese described the incident as a deliberate attack, but the motivation behind it was not clear.

* The suspect is from Tarrawingee, a town of about 400 people that is 12 kilometres east of Wangaratta.