While five others were rescued, many others are still trapped.
The incident occurred around 6pm.
Those who died were identified as Mittal Sadiya (35), her husband Jaypal (35), and son Shivraj.
Jaypal’s father Raju was under treatment along with at least five others who were rescued from the debris.
There were six houses, two each on one floor of the apartment that was constructed by the Gujarat Housing Board (GHB) some 30 years ago.
The municipal corporation had even issued a notice asking residents to vacate as the condition of the building was dilapidated and it needed to be brought down, an official said.
Jamnagar municipal commissioner DN Modi, collector Bijal Shah and other senior civic officials, and local MLA Divyesh Akbari rushed to the spot to oversee the rescue operation.
Three 108 emergency ambulances were also deployed at the spot to quickly move the rescued persons to the hospital.
KK Bishnoi, chief fire officer, Jamnagar said, “We got a call at 6:10pm. We have deployed an earthmover and other equipment to clear the debris. The entire staff of fire brigade is at the spot and those from Kalavad, Rajkot and Jam Khambhaliya were also called for the operation.”
Bishnoi said they also took the help of nearby industrial units for rescue operations.
Jamnagar BJP Lok Sabha MP Poonam Madam also rushed to the site of the accident while BJP MLA Rivaba Jadeja was in the hospital comforting the injured and relatives of the deceased.
Chief minister Bhupendra Patel announced Rs four lakh compensation for the family of the deceased and Rs 50,000 each for those injured.
