Flags are being flown at half-mast across the region, including at Farnham Castle and at Surrey Police buildings across the county.
A minute silence was also observed at Surrey Police headquarters on Thursday morning in honour of the four killed, the at least 40 people injured and all those affected by the attack.
Speaking after the silence, the Police and Crime Commissioner for Surrey David Munro said: “I am deeply shocked and saddened by yesterday’s terrible attack in Westminster and my thoughts remain with all those who have been affected.
“These events are a stark reminder of how much we depend on police officers to protect us all from harm on a daily basis.
“The swift response of the emergency services to yesterday’s attack no doubt prevented an even worse tragedy and I would like to pay particular tribute to the brave actions of PC Keith Palmer who sadly lost his life protecting others.”
The former British Army officer and Farnham councillor continued: “As Police and Crime Commissioner for Surrey, tackling the threat of terrorism is one of my key priorities and I would urge everyone in the county to remain vigilant and report any suspicious activity to police as a matter of urgency.
“We must continue to work together to defeat terrorism and those who seek to create fear and disharmony in our communities.”
Others paid the following tributes on Twitter:
*Surrey Police Federation (@SurreyPoliceFed): “Devastating to hear of the death of our brave colleague in London who lost his life keeping the public and colleagues safe.”
*Hampshire Police (@HantsPolice): “Our thoughts are with our @metpoliceuk colleagues and all those affected by the tragic events in London.”
*Surrey Fire and Rescue Service (@SurreyFRS): “RIP PC Keith Palmer murdered yesterday whilst carrying out his duties for @metpoliceuk - and the others who lost their lives in this attack.”
*South East Coast Ambulance Service (@SECAmbulance): “Our thoughts today are with all those involved & affected by incidents in London, inc our blue light colleagues @Ldn_Ambulance @metpoliceuk".
Amid BBC reports that police searches and arrests connected to the attacks have been made in Surrey, Surrey Police added in a statement on Thursday: “Surrey Police continues to review its officer deployments following the horrific attacks in London yesterday, however we were already operating at a heightened state of security against a severe threat level which has been in place since 2014, and this level continues.
“Our policing tactics and security measures are constantly reviewed and we, along with our partners, are working around the clock to keep our county and the wider country as safe as possible.
“The force continues to liaise with national and regional colleagues as the investigation unfolds.
“The public remain crucial in helping us to keep our towns, cities and communities safe, and we would urge everyone to remain vigilant when you are out and about and if you see anything suspicious then let us know using the Anti Terrorist Hotline 0800 789 321 or 999 in an emergency.
“Flags have been lowered to half-mast at our buildings across the county today and officers and staff observed a minute’s silence at 9.33am as a mark of respect to our fallen colleague, PC Keith Palmer, and in quiet remembrance of all who have been lost or injured in this incident and as a result of other such tragedies.”
Chief constable of neighbouring Hampshire Police, Olivia Pinkney said: “Our thoughts are with the families, friends and colleagues of those killed and seriously injured as a result of the events in London yesterday.
"There is currently no specific intelligence to indicate an immediate threat to any locations within the UK, including Hampshire or the Isle of Wight.
“As is standard procedure whenever an incident like this happens, whether in the UK or abroad, we are reviewing our security procedures and resources to ensure that they are appropriate and if any changes need to be made.
“We have also reviewed all pre-planned events taking place in Hampshire and the Isle of Wight in the coming days, as is normal procedure, to ensure all plans are up-to-date.
“At this time we are satisfied our plans are robust but we will continue to review the situation and follow any national guidance.
"We understand that the events in London yesterday may cause people to worry but we would renew our advice to our communities to be alert but not to be alarmed.
"We would advise members of the public to remain vigilant and if you see anything that causes you concern or raises your suspicions do not hesitate to call the Anti-Terrorist Hotline on 0800 789 321, or 999 in an emergency."