Tragedy stuck a family of four here on Tuesday when an under-construction Bengaluru Metro pillar collapsed on them, leaving a woman and her toddler son dead while her husband and another child escaped with injuries.

According to police, the incident took place around 10:30 am on Outer Ring Road near HBR Layout in the city, when the steel rod centring that was done to erect the concrete pillar for the "Namma Metro" (Bengaluru Metro) fell on their scooter. The height of the pillar is said to be over 40 feet and weighing several tonnes.

The woman and her two and a half year old son who were severely injured were immediately rushed to a nearby private hospital by the bystanders, but they succumbed to their injuries.

"Both suffered head injuries, we tried our best to save them. There was lot of blood loss already and also fall in blood pressure," doctors who treated them said.

The woman's husband, identified as Lohit and the other child, who were injured, are doing fine, doctors added.

Namma Metro and the Karnataka government announced compensation of Rs 20 lakh each to the affected family.

Addressing reporters in Dharwad, Chief Minister Basavaraj Bommai assured an inquiry into the incident and announced compensation to the bereaved.

"I just got to know about it, we will get it investigated... we will ascertain the reason for the collapse of the pillar and provide compensation," he said.

He called the incident "unfortunate" and said inquiry will be done and case will be registered against those responsible.

Deputy Commissioner of Police, Bengaluru East Bheemashankar S Guled said that a case has been registered based on Lohit's complaint and investigation will follow.

Forensic Science Laboratory (FSL) team has been called to do the mahajar and collect the samples, and based on their report it will be known if there was any negligence or shoddy work, he said adding that 'NCC construction company' was the contractor which was carrying out the work, and naturally a complaint will be taken against them.

Bengaluru Metro Rail Corporation (BMRCL) Managing Director Anjum Parvez who visited the spot described the incident as unfortunate. Indian Institute of Science has been requested to send a team to inspect and ascertain as to why the incident happened.

"According to report by our engineer all the safety measures were taken as per the standard protocol, but still the incident has happened, so we will have to do the fact finding. Whether there was any manual negligence or technical problem we will get to know from the report. If there was any manual negligence action will certainly be taken against those responsible," he said, adding that Rs 20 lakh compensation will be given to the family by the Metro rail administration.

The mishap resulted in traffic jam for some time along the stretch, even as many vehicles were plying then.

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