Police are investigating an incident where a man was run over by a van after a group of people were taking down union flags put up by Raise the Colours in Birmingham.

A man, in his 30s, suffered a broken leg that required surgery. He remains in hospital after the incident on Thursday evening in Stirchley, police said.

“The van failed to stop at the scene but was recovered on nearby Prince Road and is now being examined,” a statement from West Midlands police read. “We are viewing CCTV and social media footage as we work to identify the full circumstances of what happened.”

The Guardian has spoken to three witnesses and residents in Birmingham who said they were at the incident on Thursday evening – two of whom have given a statement to the police.

The residents said about 10 people had gathered on Pershore Road, a high street in Stirchley, at about 10pm on Thursday to take down flags put up earlier in the day by Raise the Colours. They claimed men who were wearing jumpers with the group’s logo arrived at the scene shortly after they did and were allegedly “really aggressive” and “seemed like they were really wanting to fight”.

Raise the Colours has put up thousands of union and Saint George flags across England and attracted criticism for spreading anti-immigrant rhetoric. Last month, Oxfordshire council issued a legal notice banning the group from putting up flags and said staff and residents had been “subject to abuse and threatening behaviour”.

Irial Eno, a 36-year-old doctor and resident in Stirchley, said she was “punched” by a man wearing a Raise the Colours hoodie. Video footage taken by Eno and shared with the Guardian corroborated this account – and showed the same individual ripping off a face mask from another woman’s face. In the video, the men are heard calling the group a “fucking disgrace” and “traitors to your own country”.

Eno, who is friends with the man that was run over, said she had not realised he had been hit until she heard a man, wearing the Raise the Colours logo, say so. “It was only [when] one of the guys from the RTC. He was saying ‘someone’s been hit’,” Eno said.

The Raise the Colours co-founder Ryan Bridge said in an interview with the BBC that the area was “hijacked” by the “far-left”, adding that they looked like “they were there for trouble”. He said he knew nothing about the road crash, adding that the group does not “condone any violence”.

Eno said her friend has been “seriously injured” by the incident and she stayed with him in hospital until 3am. “He’d been hit initially and was there lying on the floor by himself and [we] hadn’t realised because we were all caught up in this other harassment,” she said.

“He’d been too scared to call out because he’d been hit and then the van, the cherrypicker, had driven off and he hadn’t wanted to call out in case they’d come back.”

Another Birmingham resident, who did not want to be named due to fears for his safety, said men wearing the Raise the Colours logo had “confronted us in a very aggressive and abusive fashion” after they had taken down three flags on the high street. He said the Raise the Colours logo was on the side of the van.

“The first thing I saw were two men filming coming down the street wearing Raise the Colour logos on their shirts, shouting and abusing us. I got pushed, a guy with a pole had to wrestle to keep the pole because they tried to wrestle it from him. It was very aggressive.

“It was very intimidating and they clearly were there to both abuse and to try and frighten us.”

Al Carns, the local Labour MP, said in a letter to the acting chief constable of West Midlands police that he had been contacted by “dozens of residents” about the incident, who described “harassment, intimidation and physical assault” by members of Raise the Colours. He said the accounts were “troubling” and he wanted to discuss “preventative measures” to stop a similar incident from recurring.

David Clarke, a 65-year-old management consultant who lives in Stirchley and was also at the incident on Thursday, said he had repeatedly contacted police, the local council and Carns calling for tougher action to be taken against Raise The Colours.

Clarke, who has been involved in action to take down flags since September, said the incident was shocking but not surprising. “ We have been saying for a long time that the Raise the Colours guys were a serious threat.”

Brummies United Against Racism has renewed calls on newly elected councillors to take urgent action against Raise the Colours.