Bosses at Peterborough Hospital say they are full and are beyond black alert status.
Patients are being asked to consider all treatment options before attending A&E.
The hospital say they are running at 107% capacity and are working to reduce the pressure on the emergency department.
- Video report by ITV News Anglia's Stuart Leithes
A man has been arrested in connection with a fatal hit-and-run in Yaxley yesterday in which two pedestrians died.
The 38-year-old man from Essex was arrested in Chelmsford late last night - 76 miles away from the scene of the crash.
He's been arrested on suspicion of causing death by dangerous driving and ABH and is currently being questioned in Chelmsford before he is transferred back to Cambridgeshire later today.
The two victims, who are believed to be in their late teens or early twenties, were hit by a BMW on the B1091 Broadway road yesterday.
Police are investigating whether the discovery of a briefcase stuffed full of cash in Yaxley is connected to a suspected hit-and-run in the area.
Officers are also looking into a call from a member of the public that a man broke into their home in the village today.
It's not yet known whether the incidents are linked to the deaths of two pedestrians on the B1091 Broadway road this morning.
The driver of the vehicle fled the scene of the crash and a hunt to find him is ongoing.
- Video report by ITV News Anglia's Claire McGlasson
It's believed that two men who were killed after being hit by a car near Peterborough today were aged in their late teens or early twenties.
The pedestrians were struck by a BMW in Yaxley just after 11am.
The driver left the scene on foot and police are still looking for him.
Police are also looking into whether a call from a member of the public reporting a man entering their home is connected to the incident, while the discovery of a briefcase stuffed full of cash which was found in the area is also being investigated.
Police are searching for a driver who fled the scene of a suspected hit-and-run crash near Peterborough today.
The man's BMW struck two male pedestrians on the B1091 Broadway road in Yaxley just after 11am.
The air ambulance was called to the scene but the men couldn't be saved.
The driver, who is believed to be in his 40s, ran away and officers are currently trying to find him.
The police helicopter is being used in the search.
The road is currently closed in both directions and motorists are ask to avoid the area.
Two people have been killed in an 'incident' near Peterborough.
Police were initially called to reports of a road crash at Broadway in Yaxley just after 11 this morning - but now say it is not clear what happened.
The road is currently closed in both directions and drivers are being asked to avoid the area.
More details as we get it
Peterborough City Hospital has declared a 'critical internal incident' due to a lack of available beds.
The hospital says patients are facing significant delays to be admitted to wards because of an unprecedented rise in the number of people needing emergency treatment.
To help ease the pressure, staff are asking people to only turn up to A&E if absolutely necessary.
I would like to thank patients and their relatives for their co-operation and understanding, particularly those who have experienced a long delay in waiting for a bed. We are doing all we can to ensure patients do not have to wait any longer than is necessary, but this is being hampered by the larger than usual volume of people needing hospital care at present.
We have called in additional staff to assess patients coming to us in an emergency and to support our ward teams in discharging those patients who are now well enough to go home. However, we are bracing ourselves for a challenging first week of the new year as we know it will take a few days before we can re-establish a smoother flow of patients in and out of hospital.
Regionally, other hospitals are also under significant pressure so we would ask that people only attend their local Emergency Department for critical situations, such as choking, chest pain, loss of consciousness, severe blood loss, broken bones or trauma, difficulty breathing, deep wounds or suspected stroke.
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A mother of two from Cambridgeshire was diagnosed with cancer after a chance encounter with a family doctor in Cyprus.
Danielle McCulloch from Crowland near Peterborough was getting married on the island, where her grandmother lives, when they bumped into the GP who spotted an unusual lump on her neck.
When she looks back at her wedding photos Danielle says she can see where her neck had swollen because of a tumour.
She's backing a new campaign by Cancer Research UK called Right Now, which highlights the importance of getting symptoms checked by a doctor.
Click below to watch a report by ITV News Anglia's Stuart Leithes
Mohammed has topped the list as Peterborough's most popular name for baby boys for the ninth year in a row.
That's according to figures released by Peterborough Register Office.
Oliver was the second most popular name in 2016, followed by Harry in third place.
The number one name for baby girls was Amelia, followed by Sophia and Olivia.