A grief-stricken father has described how he rushed to help a fatally injured man during riots in the English city of Birmingham, only to find his 21-year-old son was also lying dying on the street nearby.

Tariq Jahan desperately tried to save his injured son Haroon, who was run over along with two other men as they stood in a group of people trying to protect properties against gangs of looters running amok in England's second city on Tuesday night.

All three men died after the car was driven into the crowd, and police have arrested a 32-year-old man on suspicion of murder.

"I heard the thud, ran around and I saw three people on the ground," Tariq Jahan told reporters.

"My instinct was to help the three people. I didn't know who they were, who'd been injured. I helped the first man, and somebody from behind told me my son was lying behind me.

"So I started CPR on my own son. My face was covered in blood, my hands were covered in blood."

Mr Jahan says Haroon had come out in the street with other men from the community to defend property after rioters smashed up a petrol station, broke into a social club and beat up neighbours.

Why? Why?

Sorry, this video has expired Three men killed in Birmingham riots

"Why? Why? The guy who killed him drove directly into the crowd and killed three innocent guys," he said.

"Why? What was the point of doing it? I don't understand."

"We are here defending the community of all the problems that are going on in the country. He was trying to help his community.

"I lost my son. Step forward if you want to lose your son. Otherwise calm down and go home."

He said his son, a mechanic, was well-liked and well-known in the community.

"You lose your son, I can't describe to anyone what it feels like to lose your son," he added.

"People came out of prayers and they were protecting the area. My friends were targeted - they were standing on the side of the road and the car just came and ran them over," witness Kabir Khan Isakhel said.

Another witness said the incident happened after a car was set ablaze in a nearby street and youths gathered, prompting local people to defend a local shopping area.

"They lost their lives for other people, doing the job of the police," Mohammed Shakiel said outside the hospital where the men were taken

In this video, local man Arjun Panesar tells ABC News Breakfast that the situation in Birmingham is calm but tense, and does not rule out a repeat of this week's disturbances.

Sorry, this video has expired Birmingham calm after days of riots

As the community took stock, Tariq Jahan urged locals not to take revenge and called for the law to be allowed to take its course.

"I don't blame the government, I don't blame the police, I don't blame nobody," he said.

"I'm a Muslim, I believe in divine fate and destiny, and it was his destiny and his fate, and now he's gone."

Riots had spread to Birmingham on Tuesday after three nights of violence in London.

ABC/wires