A man and woman have been found dead with stab wounds inside their home in Blackburn.
Police were called to the terraced property on Hardman Street at 8.22am on Monday after reports that two people had been injured.
Two people were found inside, and both were pronounced dead at the scene.
A large police cordon was quickly put in place around the house, with a forensic tent erected outside the front door.
Several back alleys have also been sealed off as detectives continue to investigate.
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A man in his 40s has since been arrested on suspicion of murder and remains in custody.
Police have said they do not believe there is any wider threat to the community.
Neighbours woke to a major police presence as detectives carried out door-to-door enquiries.
One couple living in the next block said: ‘When we got up, just after 8am, we looked outside and it was all there then. It was a bit of a shock.’
Terence, who has lived on Hardman Street for ’30 odd years’, said police allowed him back into his home after he returned from work and discovered the crime scene.
‘It used to be quiet round here but it’s not anymore,’ he added.
Another resident said the couple were elderly and attended a nearby mosque, describing them as ‘very private’.
Lancashire Police said the pair had not yet been formally identified and post-mortem examinations would take place in due course.
The force said a dedicated team was carrying out CCTV checks, forensic work and house-to-house enquiries.
Detectives are also working to establish what happened and why, with the motive still unclear.
A police spokesperson said: ‘We are at the early stages of establishing exactly what has occurred and why.
‘Detectives are continuing to work to establish a motive for this tragic incident; however, we don’t believe there is a wider threat to the community.’
The force said the police presence in the area would remain increased over the coming days while enquiries continue.
Officers are appealing for anyone who saw or heard anything suspicious in the area over the past 24 hours, or who has CCTV, dashcam, mobile phone or doorbell footage, to come forward.
Anyone with information can contact police on 101, quoting log 0252 of September 7, 2026.