A number of roads have been closed in Edinburgh city centre due to a "serious road traffic incident".
Police Scotland said officers responded to reports of a pedestrian being struck by a vehicle at around 7:30pm on Saturday.
Enquiries are ongoing, the force added.
Members of the public have been asked to avoid the area until further notice.
Edinburgh Cowgate Lockdown: 'Severed Head' Found, Pubs Evacuated
Pubs in the area were evacuated after dozens of officers were called to the Cowgate just after 8pm.
Eyewitness claimed that the "severed head" was found in a nearby street.
Photographs shared online and sent to the Record have not yet been verified.
Police Scotland said they are dealing with a road traffic incident. Comments left on the force's Facebook page claim the images of the alleged incident are "gruesome" and "horrific".
Forensic officers have now set up two separate tents at the scene.
Katie McLaughlin, from Dumfries, had been in Bannerman's Bar in the Cowgate when she and her friends were locked in after around 8pm.
The 31-year-old told the Record: "We were in Bannermans having a drink and went to leave but a member of the staff stopped us. He said police were outside and a severed head had been found in the Cowgate. I almost laughed because it's Halloween weekend and I thought it was a prank. We went to the bar where the staff said, no, it's real.
"They said that the police had ordered them to shut the pub. They then let us all leave by the back door but we were able to have a look down the street.
"I saw three police cars and five police officers and a small silver tent. The police were taping off the area. We are in another pub now. The whole area is sealed off. It just seems so surreal."
Another eyewitness said: "Police just appeared and started putting tape up. Whatever it is, it looks pretty serious. There doesn't look to be any cars inside the cordon anyway."
Blair Street, Guthrie Street and Candlemaker Road remain closed off.
Several surrounding night time venues have been ordered to close to allow police investigations to take place. A number of bars and nightclubs were due to host Halloween-themed events.
Edinburgh Cowgate: Police Respond to 'Road Traffic Incident'
A huge police presence has been spotted on Cowgate, with several surroundings streets also cordoned off. Officers say they are responding to a "road traffic incident."
Images from the scene show the bottom of Niddry Street taped off with around five police cars in attendance. An eye witness claims the incident took place just before 7.30pm.
They added: "Police just appeared and started putting tape up. Whatever it is, it looks pretty serious. There doesn't look to be any cars inside the cordon anyway."
A Police Scotland spokesperson said: "Emergencies services are responding to a road traffic incident in Cowgate, Edinburgh. Blair Street, Guthrie Street, Candlemaker Road are closed. Motorists are advised to avoid the area and use alternative routes. Thank you for your patience."
We will update this story with more information as we get it.
Edinburgh Road Traffic Incident: Police Investigation Ongoing
At around 7.30pm on Saturday, November 2, police officers responded to reports of a pedestrian being struck by a vehicle.
Blair Street, Guthrie Street and Candlemaker Row are closed and buses are unable to serve the Grassmarket in both directions.
Following the incident Police Scotland advised: “Emergencies services are responding to a road traffic incident in Cowgate, Edinburgh. Motorists are advised to avoid the area and use alternative routes. Thank you for your patience.”
Pictures shared on social media show a large police cordon in place near Niddry Street. Several police vehicles and a forensic team can be seen in attendance.
Providing an update shortly before 11.40pm, a Police Scotland spokesperson said: “Officers in Edinburgh are currently dealing with a serious road traffic collision in the Cowgate area of the city. Shortly after 7.30pm on Saturday, November 2, we responded to reports of a pedestrian being struck by a vehicle. Enquiries are ongoing.
“As a result, Blair Street, Guthrie Street and Candlemaker Row are closed to pedestrians and traffic. Members of the public are asked to avoid the area until further notice.”
Lothian Buses has announced service 2 has been diverted following the incident. The bus operator stated: “Due to a road closure, buses are unable to serve the Grassmarket in both directions and are instead diverted towards the Jewel via Fountainbridge and Lauriston Place.
“Buses travelling towards Hermiston Gate will operate via Lauriston Place and Lady Lawson street until further notice.”
Police Scotland and the Scottish Ambulance Service have been approached for comment.
Edinburgh Cowgate Incident: A Night of Chaos
Emergency services raced to the area at around 8pm on Saturday night. Blair Street, Guthrie Street and Candlemaker Road currently remain closed off by police.
Pictures from the scene show a blue tent within a cordon surrounded by forensic officers, Daily Record reports.
31-year-old Katie McLaughlin found herself amidst the chaos at Bannermans Bar, where she and her friends were abruptly informed that they needed to vacate the premises.
Hailing from Dumfries, Katie, who was on a weekend break in the Scottish capital, said: "There was a band playing at the back when an announcement was made that police were outside and had ordered them to shut the pub."
She added: "We finished our drinks and went to leave but a member of the staff stopped us."
The staff directed the patrons towards an alternate exit, with Katie adding: "They then let us all leave by the back door but we were able to have a look down the street.
"I saw three police cars and five police officers and a small silver tent. The police were taping off the area."
Katie described the scene as incredibly unusual: "The whole area is sealed off. It just seems so surreal."
A statement from Bachata Blues Edinburgh reads: "Following police instructions, all Cowgate venues are going to be closed tonight due to a major incident. All ways to enter Cowgate are cut off. Unfortunately, we have to cancel tonight's event as Mash House will remain closed all night, following police instructions. We will be back soon & hope to reschedule our night as soon as possible!"
A statement from Police Scotland Edinburgh reads: "Emergencies services are responding to a road traffic incident in Cowgate, Edinburgh. Blair Street, Guthrie Street, Candlemaker Road are closed.
"Motorists are advised to avoid the area and use alternative routes. Thank you for your patience."
