According to NAN, eight persons were involved in the ongoing building construction when the incident occurred at about 2pm.
An eye witness said those trapped were workers and the site engineer.
“They were working at the site when suddenly we heard a loud sound which happened to be the building that collapsed.
“People came to rescue two person but six others are still buried in the debris,” the source said, urging the state government to come with heavy equipment to rescue others.
Mr Ifeanyi Iburu, the Divisional Police Officer for Onitsha Central Police Station, led a team of security operatives to ensure adequate security of lives and property.
Personnel from the Nigerian Red Cross, Nigeria Security and Civil Defense Corps as well as sympathizers were part of those attempting to rescue the remaining six.
Confirming the incident, the state Chairman, Nigerian Red Cross Society, Prof. Peter Katchy said the rescued victims had been rushed to the hospital for medical attention.
“One of the persons rescued by Red Cross is at the intensive care at Holy Rosary Hospital Waterside, Onitsha, while another is at General Hospital Onitsha.
“Four are still trapped under the debris of the collapsed building including the Site Engineer,” he said.
He noted that an excavator and some earth moving vehicles were expected to assist in the rescue mission.