Gabby Giffords, the former Arizona Representative who survived a vicious assassination attempt in 2011, said she was 'sickened' by the murder of a U.K. politician Thursday.

Speaking on Twitter, Giffords talked of her horror at the death of British Member of Parliament (MP) Jo Cox, 41, who was shot in the head and stabbed by a man while going to meet her constituents in Northern England.

Giffords, 46, was herself meeting constituents in 2011 when a man opened fire, hitting her in the head, injuring 18 others and killing six. She said the attack on Cox was due to the 'coarseness in our politics' and that something must be done.

Meanwhile, Hillary Clinton said 'It is cruel and terrible that her life was cut short by a violent act of political intolerance.'

Scroll down for video

'Sickened': Gabby Giffords (pictured in April) said she was 'sickened' to learn of the shooting and stabbing death of British lawmaker Jo Cox on Thursday. Giffords herself was shot in the head in 2011

Rising star: Jo Cox (left) was among the rising stars in the British Parliament before she was stabbed and shot dead on the streets of her constituency in the county of Yorkshire. Her attacker (right) was caught by police

'Cruel': Hillary Clinton (pictured in 2011) said that Cox's murder was 'cruel and terrible' and that the U.S. and U.K. should honor Cox 'by rejecting bigotry in all its forms... as she always did'

Cox, an MP for the left-wing Labour party, was heading to a meeting with voters in her constituency when she was attacked. 'Loner' Tommy Mair, 52, was identified as the attacker by locals.

The married mother-of-two was punched and kicked to the ground by her attacker before being shot three times - once in the head - with a sawed-off shotgun and repeatedly stabbed with a 'foot-long hunting knife' as she lay helpless on the ground.

'Absolutely sickened to hear of the assassination of Jo Cox,' Giffords said Thursday morning in a series of Tweets. 'She was young, courageous, and hardworking. A rising star, mother, and wife.'

She went on to say that he 'assassination... at the hands of a man driven by hatred is a manifestation of a coarseness in our politics that must stop.

'The scores of events that I and so many others like Jo Cox have hosted represent the importance of a democracy connected to its citizens.

'I grieve for Jo Cox’s family, friends, constituents, and for the people of Great Britain,' she concluded.

And Hillary Clinton said in a statement that she was 'horrified' by the assassination. 'By all accounts, she was a rising star,' Clinton said.

'Her maiden speech in Parliament celebrated the diversity of her beloved Yorkshire constituency, and passionately made the case that there is more that unites us than divides us.

'It is cruel and terrible that her life was cut short by a violent act of political intolerance.'

She added that both the U.S. and Britain should honor Cox's memory 'by rejecting bigotry in all its forms, and instead embracing, as she always did, everything that binds us together.'

Democratic National Committee Chairwoman Debbie Wasserman Schultz Tweeted: 'What awful news. On behalf of the entire Democratic Party, our condolences to the Cox family and the U.K.'

And British Prime Minister David Cameron said the country has 'lost a great star,' as both the campaigns to leave and remain in the European Union suspended campaigning.

Suspect: Locals identified 'loner' Tommy Mair as the 52-year-old man who has been arrested by police in connection with the attack. He has been described as having right-wing views and being mentally unstable

Investigation: Forensic police officers inspect the scene of Cox's attack. Cox, who was an aid worker before becoming a politician was a left-wing humanitarian campaigner and wanted more refugees to enter the U.K.

There is unconfirmed evidence Mair, Cox's alleged attacker, supported far-Right causes and claims he had mental health problems and had been recently released from psychiatric care.

Cox was outspoken in her support for Britain to choose to stay in the European Union in an upcoming referendum, and had called for more refugees to be let into the country.

Early reports said that as he attacked her, the murderer shouted 'Britain First' - the name of a far-right group that is opposed to the European Union, refugees, and Islam.

Britain First has distanced itself from his attack.

Cox was murdered in a busy shopping street just before 1pm, while walking to a constituency meeting - advertised on posters inside the building - after attending a school assembly about three miles away.

Witnesses said a man in a baseball cap grabbed her, pulling her hair as he punched and kicked her to the ground.

As bystanders attempted to intervene in the attack, which lasted up to 15 minutes, he pulled out a large hunting knife and repeatedly stabbed the MP.

He then pulled out a sawed-off shotgun which he fired three times from just a few feet away, aiming the final shot at her head. Some witnesses claimed he looked 'full of rage' as he shot her at close-range.

Rage: Items left at the scene of the murder, where Cox was stabbed with a 'foot-long knife' before being shot three time with a shotgun. Cox's attacker was described by witnesses as looking 'full of rage' as he killed her

Police: Police raced to the scene but could not save Cox. The attacker is said to have shouted 'Britain First' as he stabbed her - the name of a far-right U.K. group. Britain First has distanced itself from the attack

A 77-year-old have-a-go-hero who tried to save the MP after seeing the attack was stabbed in the stomach. Doctors said last night that he was expected to make a full recovery.

Witness Clarke Rothwell, 42, who runs a cafe near where the attack took place, said the attacker was heard shouting 'Britain first' as he carried out the sickening attack.

He said: 'He was stabbing her with a foot-long knife multiple times while shouting "Britain first, Britain first, Britain first."

'Three times she was shot, the initial time which then she dropped to the floor, and two more times.

'The third time he got close proximity, he shot her 'round the head area. In the meantime he was stabbing her as well, he was stabbing her with his knife.'

Mr Rothwell said the 77-year-old, a friend of his, 'tried to grab him, wrestling with him,' but the killer lunged at the MP 'half a dozen times' with the knife.

He said the sound of the gunshots sparked pandemonium, with people 'screaming and running from the area'.

Arrested: Dramatic news footage shows the moment the 52-year-old man was arrested in connection with the attack on Cox

Caught: A picture was taken of the man believed to be the suspect seconds after he was tackled to the ground by two uniformed police officers

A photograph taken by a witness later shows two police officers restraining the suspect, whose hands appear to be leaking blood.

Cox, a former aid worker and an ardent humanitarian campaigner, was described by colleagues as a 'rising star' in politics.

She leaves behind her husband Brendan, 37, and her two children, aged three and five.

In a moving statement, Brendan Cox said he would dedicate 'every moment' of the rest of his life to his wife's memory.

'Jo believed in a better world and she fought for it every day of her life with an energy, and a zest for life that would exhaust most people,' he said.

'She would have wanted two things above all else to happen now, one that our precious children are bathed in love and two, that we all unite to fight against the hatred that killed her. Hate doesn't have a creed, race or religion, it is poisonous.

'Jo would have no regrets about her life, she lived every day of it to the full.'

Shotguns are legal to buy in the U.K. with a shotgun certificate, provided the guns cannot hold more than three shells.

Widower: Cox's husband, Brendan (right) said that he would make sure their daughters were raised with 'love' and that he hoped the public would 'unite to fight against the hatred that killed her'