Residents in West Lothian were warned to "stay inside and lock all doors" last night after a man reportedly went on the run with a "chainsaw".
According to locals, armed police swarmed the streets of Blackburn while helicopters scoured the area from the skies.
It is understood that a man had his arm partially "severed" in an alleged attack at the hands of another man wielding a chainsaw.
Graphic photos on social media showed the extent of the victim's injuries, which he received treatment for at hospital.
It is thought the incident took place on Rowan Drive late on Wednesday night.
One witness claimed dozens of police raced past her following the attack.
Taking to Twitter, she said: "Had just shut my eyes into what I felt like was going to be a class sleep when about 50 police go past since someone has used a chainsaw and chopped another man's arm off."
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She then added: "Now we have the helicopter out cause the guys on the run."
One local said there was "about 15 police vans here and helicopter searching".
"One person was hurt but he's being treated in hospital and it's not fatal."
"His arm is in a bad way though. Other guy hasn't been caught yet to my knowledge", said another.
Update: we have now launched a liveblog covering this ongoing incident: you can get the latest updates here.
