Madhyamgram: A suspected gang rivalry that goes back several years erupted in a hail of bullets inside a barber's shop on Friday morning, all 15 rounds of hot lead pumped into the 52-year-old man waiting for his face to be lathered.

Prakash Dey Sarkar, alias Gautam, was apparently the lone target of the 10 to 12 hitmen who came to this thickly populated North 24-Parganas neighbourhood in four motorcycles, carried out the crime and made a quick getaway in two groups.

The horrified witnesses included Gautam's brother Kartik and a group of girls walking down the main road towards their school barely 100 metres away.

Police identified the victim as a builder and materials supplier linked to several criminal cases. He was in jail custody until September for allegedly smuggling ganja.

Gautam's brother said the assailants entered the barber's shop at 10.45am and would have shot him had one member of the gang not alerted the rest that he was not meant to be the target.

"He pointed to my brother, who was in the other chair. I was dragged out of the shop while the armed men sprayed bullets at him," Kartik told Metro.

A rickshaw-puller who saw the gang exiting the barber's shop said the hitmen, their faces masked by helmets, hurled two bombs towards the main road before they fled. "I was so scared.... I took refuge behind a roadside stall," he said.

One group sped towards Sodepur while the other headed towards Madhyamgram Chowmatha on Jessore Road. The barber's shop, located inside a narrow lane, is less than half a kilometre from the local police station.

The police said a turf war between two groups involved in the construction business was possibly the trigger for the murder. "Gautam had been arrested in 2016 for peddling drugs and got bail only last September," a police officer said.

Gautam was also an accused in a 2013 murder case.

The police have detained a person suspected of acting as an informer of the rival gang and tipping off the killers about Gautam's movements.

In May 2015, a promoter and his associate were shot dead in daylight on the Madhyamgram flyover, not far from where Gautam was murdered.