Investigation launched after cop is videoed punching drunk man in face on ground after tasing him 

A criminal investigation has been launched after a Missouri police officer was videoed punching a drunk man in the face, while he lay on the ground after being tased. 

The video, which has been widely circulated online, shows two officers pinning a man down on the sidewalk outside of a bar in Columbia, Missouri, over the weekend.

In the video, two security guards and two police officers can be seen holding the man down as he is maced by one of the officers.

One of the security guards back off as the police shout at him to 'get on the ground'. 

Pictured: The officer begins throwing punches at the mans face

The officer throws a series of punches at the man who is unable to defend himself

The man is then forced to the sidewalk as he begins saying: 'I don't understand what is going on'.

He then keeps repeating this, saying: 'I don't understand what's going on, can you explain to me what's going on.'

As he continues to question his arrest again, the police officer who has him pinned to the ground tasers him and then starts punching him repeatedly in the face. 

Blood immediately begins pouring from the mans face in the video. 

As the two officers continue to pin the man down, the man again asks: 'Please just tell me what is going on.'

The cop that had punched him then pulls out his taser and again uses it on him, hitting him in the back of the legs. 

One bystander behind the camera can be heard saying: 'He is punching him in the face, oh my god.'

Another says: 'Stop. He doesn't know what is going on man.'

The unknown man lifts his head after being punched, blood can be seen pouring from his face

The as yet unidentified officer tasers the man a second time, this time hitting the back of his legs

With the two officers still pinning him down they repeatedly ask him to put his hands behind his back as they eventually manage to put cuffs on him. 

It remains unclear what the man was being arrested for, and if the police officers involved are now on leave while the incident is probed.

Columbia Police Chief Geoff Jones said in a statement Monday that he asked the Boone County Sheriff’s Department to conduct a criminal investigation.

He said: 'At my request, an independent criminal investigation into the officers' conduct is being conducted by the Boone County Sheriff’s Office. 

'The criminal investigation is already under way, and CPD will provide all available reports and recordings to the Sheriff’s Office.'

'Police use of force must be reasonable. We are thankful for those who brought this to our attention.'

DailyMail.com has approached Columbia Police Department for further comment.