Coastguard workers are searching the River Wear after reports that a car has entered the water.
Emergency services are at the banks of the river in Sunderland, near Wearmouth Bridge, while rescue boats are in the water and a helicopter has been deployed.
Police, the fire service and ambulances have cordoned off a car park, where the vehicle is understood to have gone through a barrier and into the water at around 1.30pm.
It is not yet known whether anyone was inside the car at the time.
Images show ambulances, police cars and a fire engine lining the riverbank and two rescue boats in the river.
Divers have been seen entering the water, according to an eyewitness.
The coastguard and RNLI have been seen using poles to probe the water, alongside their helicopter, which has been deployed in the search.
Dozens of panicked onlookers have gathered on either side of the river and are watching the response unfold.
Among them is a nearby resident, who did not wish to be named, who said his neighbour called emergency services after witnessing the incident from his window.

A rescue boat is seen near Wearmouth Bridge after a car went into the River Wear in Sunderland
Emergency services are at the banks of the River Wear in Sunderland after the vehicle reportedly entered the water at around 1.30pm
A water rescue unit is pictured at the scene. Members of the public were asked to avoid the area
The 31-year-old said: ‘There were loads of ambulances here, we had helicopters here at one point.
‘This is the first time I’ve ever seen anything like this around here.
‘I’ve lived here for three years, this is sad to see.
‘Some families may get some awful, awful news today.’
Posting on social media, the Mayor of North East England, Kim McGuinness said: I’m aware of the serious incident on the River Wear today after a car entered the water in Sunderland.
‘Rescue teams are at the scene and right now we must hope and pray for those involved.
‘I’ve asked the incident commander to keep me updated as we let the emergency services do their work.’
A Northumbria Police spokesperson previously said: ‘Shortly before 1.30pm today, we received a report of a car entering the River Wear near Monkwearmouth Bridge in Sunderland.
‘Emergency services are currently at the scene.
‘We would ask members of the public to avoid the area.’
A North East Ambulance Service spokesperson said: ‘We received a call to 999 at 1.23pm today to reports of an incident involving a car entering the River Wear near Wearmouth Bridge in Sunderland.
‘We sent to the scene an emergency ambulance, a clinical team leader, three officers, air ambulance and the full Hazardous Area Response Team (HART).
‘We are working closely with the coastguard and the police. We remain on scene at this time.’
A Tyne and Wear Fire and Rescue Service spokesperson said: ‘We can confirm that earlier this afternoon, two fire appliances, the TWFRS fire boat and a number of officers were dispatched to an ongoing incident on the River Wear, near Wearmouth Bridge in Sunderland.
‘Our dedicated teams are assisting blue light colleagues with the ongoing rescue efforts.’
A Great North Air Ambulance Service spokesperson said: ‘Our critical care team was activated at 1.35pm to an incident on the River Wear, near Monkwearmouth Bridge in Sunderland.
‘We had a doctor and paramedic on board our aircraft and they arrived on scene at 1.53pm.’