Chris Marriott, 46, had been out for a walk with his wife and two young sons when he stopped to help a woman lying unconscious in the street in the Burngreave area of Sheffield on Wednesday afternoon.

As Mr Marriott gave first aid to the woman, a car ploughed into him and the crowd of people who had gathered around.

In a tribute released through South Yorkshire Police, his family described him as a "wonderful husband, dad, brother, uncle - and friend to many".

"He devoted much of his life to helping others," they said, including at Sheffield College, Jubilee Foodbank and Debt Advice, Voluntary Action Sheffield, and MASKK (Manor and Castle After School and Kids Klubs).

Two men, aged 23 and 55, have been arrested on suspicion of murder and attempted murder.

The woman Mr Marriott was helping remains in hospital in a life-threatening condition, South Yorkshire Police said.

It is believed the injured woman had been involved in an altercation and several other people suffered injuries during the incident, including an off-duty midwife who had also stopped to help.

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Tareq Nayli, a Burngreave resident, was chatting on the phone at home when he "heard a lot of shouting" outside.

When he came out, he saw a lot of people and a car that seemed to have crashed, he told Sky News.

People said there were "two people underneath this car and other people fighting over there in that house".

He saw people fighting, including one "holding a big stick and hitting the other guy".

The man's face was "full of blood. You [couldn't] see anything of his face."

Another young woman was "shouting and running up and down", he said.

"And all of a sudden the police start coming, and the ambulance, and someone told me there is people underneath this car.

"The people tried to push the car up in order to pull the people [from] underneath."

He said it is usually a "very safe and very nice area", and it would be a "big disaster" and "shock" to the neighbourhood if it turned out criminals were involved.

"It's unbelievable," he said.

Mr Marriott, described as a "Good Samaritan" by police, was an IT manager for the charity Community Money Advice (CMA).

Heather Keates, the founder and chief executive of CMA, said Mr Marriott was "prepared to go the extra mile for people".

"His generosity, his care for people, his compassion for people, this was the root of who he was," she said.

Officers are appealing for dashcam, CCTV footage or information that could help their investigation.