Updated

Federal investigators are leaving the scene of a New York City explosion that killed eight people and are taking several sections of pipe with them.

The National Transportation Safety Board said Monday it has finished its work at the East Harlem scene, where two buildings were leveled March 12 in an apparent gas explosion.

The agency reported previously it had found a leak in a cast iron gas main from 1887. It now says there was more than one leak.

Sections of the pipe and a cracked section of an 1897 water main are being shipped to the NTSB lab in Washington for further examination.

The NTSB has said it's unclear if the broken water main contributed to the explosion or was caused by it.