An under-construction bridge collapsed at Jolarkandi area under Natore Sadar upazila of the district at noon yesterday, police and locals said.

Ayesha Siddika, project implementation officer (PIO) in Natore, said the 36-foot-long bridge is being constructed over the Jolarkandi canal by the Flood and Disaster Management Ministry.

Shafiqul Islam Shimul, lawmaker of Natore-2 constituency, inaugurated the construction work three months ago.

The top slab of the bridge collapsed just after casting started, injuring four workers. The injured were admitted to different clinics in the town.

Mohammad Nairuzzaman, upazila nirbahi officer (UNO) of Natore Sadar, and the PIO visited the spot.

Ayesha Siddika said the construction company, M/S Saiful Enterprise, did not follow the construction plan. As per the plan, the company had to place uncut bamboos and wooden logs under the top slab when casting. But it used split bamboos and logs, resulting in the collapse.

The PIO said Abu Sayeed, upazila sub-assistant engineer, was engaged to monitor the work, but he did not do his job properly, so he is also responsible for this incident.

Abu Sayeed and the contractor Saiful Islam went into hidden after the collapse, the PIO added.

The UNO said he will punish the guilty people.

Abdul Aziz, a resident of Jolarkandi village, said people had been protesting against the low quality work from the beginning of the construction. They did not use any rods for the ring in the wing-wall of the bridge, he added.