Tarun Purakait and Gaurav Purakait of Bishnupur in South 24-Parganas, about 202 km from Kolkata, were "forced" by Tapas Kumar Ghoshal on Tuesday night to install an air conditioner on the rooftop of Diptikona Apartment in Thakurpukur.
"When these two people were working on the terrace in the night, Sumit Bhattacharjee, who resides in the same apartment, released his two pet dogs (Alsation breed). One of the dogs rushed towards Gaurav and jumped on him. Because of this, Gaurav lost his balance and fell from the rooftop to the ground," the police said.
"Both the accused men, Sumit and Tapas, have been arrested," the police added.
Tarun, the co-worker of the mechanic who was killed, said he desperately requested Mr Bhattacharjee to hold on to his animals.
Tarun rushed down to check on the fallen co-worker and spotted building security personnel attending to the limp body of Gaurav, who was declared dead upon being taken to the DM Hospital.
A CCTV footage has captured the unfortunate fall of the worker and shows Tarun holding on to the limp body of his co-worker and pleading for help.
"I cried for help but no one came," Tarun said.