Workers at the East Harlem explosion site on March 16. (AP Photo/John Minchillo)

Federal investigators looking into the Harlem building explosion last month have released a preliminary report about the incident, and while it doesn’t really say anything massively new, it’s worth noting as the investigation moves from New York to a lab in Washington, D.C.

There is one key difference between the National Transportation Safety Board’s new report and the update it provided on March 18, six days after the explosion. The earlier update said investigators found a leak — one leak, singular — in an eight-inch gas main on Park Avenue, “adjacent to” one of the buildings that collapsed. But investigators are now saying that leak testing on the Park Avenue gas main found an unspecified number of “small gas leaks below the pavement.”

Investigators have finished their work on the scene in New York. The rest of the investigation will proceed at the NTSB headquarters in D.C., where sections of the gas main, a cracked water main and other materials will be examined.

The explosion on March 12 leveled two buildings, killed eight people and injured dozens more.