A family of two British grandparents and their adult son were violently assaulted in Thailand by a gang of “drunk” thugs who were reportedly targeting “westerners”.

Confronting footage of the vicious assault shows the moments when two grandparents and their adult son were set upon and left unconscious at the Hua Hin resort, 250km from Bangkok, during Thai New Year on April 13.

Lewis Owen Senior, 68 and Rose Owen, 65 remain in hospital at Thailand’s coastal resort Hua Hin following the vicious attack that knocked them and their son Lewis Owen Junior, 43, out cold.

A witness who had been drinking at the bar where the attack happened said the gang had been looking to target “westerners”, the UK Mirror reported. Mrs Owen, who the video shows was punched in the face sending her crashing to the ground, required several operations to help reduce the swelling on the brain.

Her son, a graphic designer who lives in Singapore, needed 16 stitches in three areas of his head, while his elderly father needed six stitches in his forehead and suffered heavy bruising and two black eyes in the attack.

It was reported a female Good Samaritan was also beaten when she tried to stop the assault on the elderly woman. Mr Owen Junior said he was celebrating his father’s birthday with his parents on the evening of the assault.

He told the newspaper he catches up with his folks twice a year but next time they won’t be meeting up in Thailand. “I’m, not going back to Thailand again. “Mum and dad won’t be either. Never, ever again.”

The video shows the family walking through a crowded street during Thai New Year celebrations. The son is knocked down and takes some time to get himself off the ground. The senior couple confronts their son’s attackers and after a bit of a scuffle one of the gang members serves the grandfather a flying punch to the face and he hits the floor.

The son is again knocked out, before one of the thugs repeatedly stomps on his head and kicks him while he lay unresponsive. Moments later Mrs Owens is punched in the face, sending her to the ground. She tries to sit up but one of the men kicks her in the jaw, knocking her unconscious.

Once the gang members disperse some bystanders come to their aid and the video cuts. Mr Owens Junior told the Mirror the attack was “random” and the family was on its way back to the hotel. Police Colonel Chaiyakorn Sriladecho confirmed four people in their 20s and 30s were arrested in relation to the attack.

He said three of the men would face charges of causing grievous bodily harm in a Hua Hin court, where the judges have sped up witness examination because the family is due to return to the UK next week.

He said the men were sorry for the brutal attack and it would not have happened if they weren’t drunk. “The perpetrators said they were drunk. They have also apologized to the family,” Colonel Chaiyakorn said.

A spokesman for the Tourism Authority of Thailand said: “An investigation is in process and the suspects will soon be under the jurisdiction of the court. “If found guilty, the perpetrators of this incident will face full justice under Thai law.”