A 34-year-old man is being questioned on suspicion of murdering two women in separate attacks minutes apart.
Cleveland Police received a report that a woman had been seriously injured at an address in Mapleton Crescent, Redcar, at 8.45pm on Wednesday evening.
Just seven minutes later, at 8.52pm, a second report was received from a member of the public reporting that a woman was being violently assaulted in Byland Close.
Police said both women died after suffering serious injuries.
A man was arrested on suspicion of two counts of murder a short time after the incidents.
Neighbours in Mapleton Crescent said the victim lived alone in the semi-detached bungalow, where there was a small police cordon and two uniformed officers guarding the scene.
Less than a mile away in Byland Close, a white forensics tent was still in place outside a modern terraced house in a block of three homes. An empty ambulance remained at the scene, parked at an angle to the front door of the property. What appeared to be blood could be seen on the white front door of the neighbouring house.
Locals said the victim in Byland Close was a mother of three.
Toys and play equipment could be seen in the rear yard of the house.
There was a much larger police cordon around the house in Byland Close, which is close to playing fields and near a busy road with a care home and children's centre nearby.
A bunch of flowers was left near the scene, paying tribute to the victim and her "beautiful" children.
In Mapleton Crescent, neighbour Dora Gillespie, 74, said the woman who lived there had been at the property for about a year following the death of the previous elderly resident.
The neighbour said: "It's very, very shocking. We've not had owt like this round here."
Mrs Gillespie heard nothing on Wednesday night, having closed her blinds and watched television, and the first she knew was after hearing of the incident on the news on Thursday morning.
Leonie Ing, 92, who lives opposite the bungalow, said the victim was disabled and had visits from a carer.
The former post office worker said: "I didn't know the lady.
"I once saw her walking down the road with her son and his girlfriend.
"They stayed with her when she first moved."
Mrs Ing said the neighbour lived alone.
Redcar's Labour MP Anna Turley spoke in the House of Commons about the murders.
She said: "Last night two women were brutally murdered on the Lakes Estate in Redcar.
"A 34-year-old man has been arrested.
"I am sure the whole House would join me in expressing their horror and their sadness at these terrible murders and to send our thoughts and heartfelt condolences to the victims' families, particularly the children, and also to the local community at this terrible time."
The MP added that a woman is killed every three days in the UK and she said agencies working with the victims of domestic violence were "stretched to breaking point".