Image source, AFPImage caption, A picture from the site of the collapse shows one person who has been treated for injuries

Several people are feared trapped after a high-rise building under construction collapsed in Nigeria's commercial hub, Lagos, witnesses say.

Images from the scene show crowds gathering close to a huge pile of rubble. Police are struggling to cordon off the area.

The local authorities have put into place an emergency response plan to deal with the situation.

Lagos has seen several building collapses in recent years.

The causes of this incident are still unclear, but residents have joined rescue operations and have criticised the authorities for not responding quickly, Reuters news agency reports.

The head of the Lagos state emergency management agency has said it was unclear if there were fatalities, but pictures show rescue workers carrying one body away from the scene.

"It is a 25-storey building still under construction. Many workers are trapped under the rubble. We are trying to rescue them," Oke-Osanyintolu, is quoted as saying by the AFP agency.

Image caption, Efforts to dig through the rubble have begun

Some of the workers at the site said their colleagues were still trapped in the rubble, the report added.

"I feel so bad because the people that are inside they have family," one of them identified as Latif Shittu said.