A 20-story building in an up-market area in Lagos collapsed on Monday, killing at least five people. Authorities said the building that collapsed was a luxury apartment that was still under construction.

The building was located on Gerald Road in Laos' affluent Ikoyi neighborhood. There was reportedly no warning and the building just suddenly collapsed.  Authorities said there might still be people trapped under the rubble.

Firefighters, police, and rescue workers from multiple agencies have scrambled to locate survivors. The rescue operation is still ongoing. The Lagos State Emergency Management Agency said that it has confirmed at least five deaths as of Tuesday. The agency could not yet speculate on how many people are missing.

Rescue workers are still trying to interview witnesses in an attempt to ascertain exactly how many people were inside the building before it collapsed. One witness said that he saw the building suddenly move from side to side before it collapsed.

The building had been under construction for the past two years and was nearly completed. Authorities said several of the developer's agents and some prospective buyers were inside the building. Rescue workers have only been able to recover three survivors since the building collapsed.

Authorities said they are planning to launch an investigation to find out the cause of the collapse once rescue efforts are completed. Fire engines and ambulances are currently on the scene to aid in the rescue efforts.

"We just heard an unusually loud sound from our office building and the building we're occupying was vibrating. So, I looked through the window, only to see the building collapsing floor after floor. And of course, we all ran to safety," one witness who was working at a nearby building said.

Before rescue workers arrived, locals and those living and working nearby hurried to the site to help find survivors. Reports said that hundreds of people were gathered around the site digging through the rubble by hand. It reportedly took several hours before emergency response teams arrived at the scene, sparking anger amongst the gathered crowd.

Rashid Olamilekan, a passerby who witnessed the collapse, had rescued three construction workers from the rubble. Olamilekan said he was simply compelled to save his fellow Nigerians.

The collapse is the latest such incident in the city of nearly 20 million people. In 2019, two separate buildings collapsed killing several dozen people.