A sub-inspector and fourcivic volunteers were beaten up by a mob while enforcing lockdown at Baruipur area of South 24 Parganas district on Tuesday, police said.Sub-Inspector Dhananjay Mukherjee and four civic volunteers were beaten up by a mob with bamboo sticks when they asked a large number of people who have gathered before a tea stall to maintain social distancing at Khiristola under Baruipur police station, they said.The mob also damaged the police vehicle, they said.On getting information about the attack, a big force led by SDPO Baruipur went to the spot and rescued the policemen and sent them to hospital.Eighteen persons have been arrested for attacking the police personnel, they added.