North Wales Police attended the incident shortly after 2.45pm on Wednesday. Officers say they are working to identify the full circumstances of the incident.
Three people have died after a road collision in Anglesey, police have confirmed.
North Wales Police say they responded to the incident in the town of Beaumaris shortly after 2.45pm on Wednesday.
Police attended Alma Street, close to Beaumaris Pier, along with ambulance and air ambulance crews.
Officers say work is continuing to establish the full circumstances of the incident.
The public is urged to avoid the area around High Street, with police warning it will be closed for some time.
Chief Inspector Caroline Mullen-Hurst said: "Sadly, we can confirm that three people have been fatally injured in the incident.
"We are appealing to anybody who witnessed the incident that hasn’t already spoken to officers, or anybody who might have dashcam footage, to please get in touch."
The force says it will issue a further update in due course.
A spokesperson for the Welsh Ambulance Service confirmed two emergency ambulances, once Cymru high acuity response unit paramedic, one advanced paramedic practitioner, one duty operational manager and one locality manager were sent to the scene.
"We were supported by pre-hospital immediate care specialists from North Wales emergency doctors service and advanced critical care support was delivered by the emergency medical retrieval and transfer service in a Wales Air Ambulance charity helicopter," the spokesperson added.
A Wales Air Ambulance spokesperson said two crews were sent by air and arrived on scene at 3.06pm.
Its involvement in the response concluded at 4.28pm.