Expressing "shock" over the tragedy, Banerjee promised all assistance to the bereaved families.
"Our government is providing Rs 5 lakh each to the victim's family and render all assistance to them," Banerjee said in one of a series of tweets, describing the incident as "unfortunate".
The state government has deputed additional director general of police, South Bengal, Sanjay Singh, to Kashmir to find out the details, she said.
"In a most unfortunate incident in Kashmir on yesterday (Tuesday), five innocent labourers were brutally killed in a pre-planned manner. We are totally shocked!" the chief minister tweeted.
The chief minister said presently there are no political activities in Kashmir and the entire law and order was managed by the Government of India.
"We, therefore, demand a strong investigation so that the real truth comes out," she said.
Banerjee said state's ruling Trinamool Congress MPs and MLAs have reached Murshidabad to meet the family members of victims.
Earlier, the chief minister said she was deeply saddened by the brutal killings.
"Words will not take away the grief of the families of the deceased," Banerjee said in a social media post.
Five workers from Bahalnagar village in Sagardighi block of Murshidabad district were killed and another injured in a terror attack in Kashmir's Kulgam district on Tuesday.
( With inputs from IANS )