Rescuers freed 12 people from the rubble after a building collapsed in the West African country’s second city.

Twelve people were rescued on Thursday and no one was killed after a three-story building under construction collapsed in Sierra Leone.

The incident occurred in the southern city of Bo, the second-largest city in the West African country after the capital, Freetown.

Four of the rescued were hospitalised and released and eight others were still being treated, Southern Province Assistant Police Inspector General Kapri Saidu Kamara said.

He said the building collapsed Wednesday as concrete was being poured onto the third floor because the pillars were not strong enough. Many construction workers were able to escape the scene along the Bo-Kenema highway.

Joseph Kpanabom, the Southern Regional Surveyor, told local newspaper POLITICO there was poor construction and sub-standard materials used.

More than 80 people were working on the building at the time, police said.