Three people are believed to have been stabbed to death in a stairwell to a hotel in Glasgow city centre.
It is understood that a suspect was shot dead by police.
The Scottish Police Federation have confirmed a police officer was stabbed. Armed police remain at the scene outside the Park Inn in West George Street.
A statement from Police Scotland said the situation was “contained” and there was no danger to the general public.
First Minister Nicola Sturgeon said reports of the incident were “truly dreadful” and she was being “updated as the situation becomes clearer”.
She added: “My thoughts are with everyone involved.”
Police Scotland Assistant Chief Constable Steve Johnson urged people to avoid the area.
He said: “Armed police officers attended the incident and I can confirm that a male suspect was shot by an armed officer.
“I would like to reassure the public that at this time we are not looking for anyone else in relation to this incident.
“I can also confirm that a police officer was injured while dealing with the incident and that officer is receiving treatment in hospital.”
Witness Craig Milroy, who saw the aftermath of the incident from an office building nearby, said he had seen four people taken away in ambulances.
He told the PA news agency: “I saw a man lying on the ground, of African descent, with no shoes on. He was on the ground with someone holding his side – I don’t know if it was a bullet wound, a stab wound, or what it was.”
Mr Milroy said the man was one of the four taken away by medics and believed him to be a victim of an attack.
He added: “After that we saw commotion, ambulances further up and we saw armed police all running into the hotel next to the Society Room.
“We were still standing outside, after that the police all came down, the riot police and triage team told us to go back in and lock the door.”