An Australian mother of two was hit by the London attacker on Westminster Bridge.

A South Australian mother of two is among more than 40 people injured after a man drove through a group of pedestrians on London’s Westminster Bridge, before driving into the grounds of Britain’s Parliament buildings and stabbed and killed a police officer.

Trish Neis-Beer, a German national who lives and works in the Adelaide Hills, is recovering in hospital after she was hit by the car driven by the attacker.

She was in London visiting her daughter Paige, who is currently working in the city. She had been updating friends and family during her trip by posting photos on Facebook.

Trish's mother, Evelyn Neis-Conrad, told News Corp Australia her daughter was "safe, alive" and was "being well looked after".

"I have no idea when she can come home, as long as she comes home safe," she said.

Trish's neighbour Viv Lewis described her as a "lovely" woman and said knowing that someone she knew was involved in the attack "really brings it home".

News of her recovery comes as the identities as the three people killed in the attack - alongside the attacker himself - have been revealed.

Forty-eight-year-old police officer Keith Palmer - who had been working with the police force for 15 years - was named as the man stabbed outside the British parliament.

Mother-of-two Aysha Frade was killed while on her way to collect her kids from school by the car that ploughed into pedestrians on London's Westminster Bridge.

United States citizen Kurt Cochran had been enjoying a trip to London in celebration of his 25th wedding anniversary with his wife when he was killed.

His wife, Melissa, remains in hospital after she was also seriously injured in the attack.

A woman who was seen plunging from the Westminster Bridge into the Thames river during the attack has been named as 29-year-old Romanian architect Andreea Cristea, according to The Independent.

It remains unclear whether Cristea leapt from the bridge as a result of her injuries, or to avoid being hit by the car as it drove through a group of pedestrians.

Romanian Ambassador Dan Mihalache said the woman sustained serious head injuries and has badly damaged lungs as a result of the fall.

She was rescued from the water by a City Cruises boat, whose crew spotted her body floating downstream.

She is currently fighting for her life in hospital, and is said to be in a serious condition.

So far, seven people have been arrested after overnight raids were conducted following the attack at Westminster.