Two persons died inside an under-construction septic tank in West Bengal's Jalpaiguri district on Sunday, police said.
The incident happened in Teshimala in Malbazar police station area, they said.
The deceased, Aminul Islam (24) and Sahid Ahmed (20), were construction workers and they entered the septic tank to remove the shuttering that was set up to build its concrete roof.
It is suspected that they died due to asphyxiation, police said, adding that the bodies were sent for post-mortem examination.
An investigation into the incident is under way, police said.