21-story apartment building being built in Lagos, Nigeria collapsed on Monday with at least three dead and many people feared trapped under the rubble.

The building, located in the Ikoyi area of Lagos, has been under construction for the past two years. Witnesses said construction teams were at the site on Monday waiting for an excavator to arrive when the building suddenly collapsed.

Hundreds of people were seen at the site digging through the wreckage by hand, CNN reported. For about two hours after the collapse of the building, an official emergency response had not started. Obafemi Hamzat, deputy governor of Lagos, later arrived at the site. The Nigerian Red Cross is also now at the site.

It is currently not known what caused the collapse. However, building collapses are relatively common in Lagos where the Associated Press reports that enforcement of building code regulations is weak. In 2019, several people died after the collapse of two separate buildings — one housing a school.

The building which was housing a school had been listed for demolition by the Lagos State Building Control Agency (LASBCA) due to structural failure. The Lagos State Governor, Akinwunmi Ambode, also disclosed the school was operating illegally.

Many Nigerians took to social media at the time to vent their anger over yet another avoidable tragedy that could have been prevented if the systems were working.