Federal investigators have finished picking through the rubble of the March 12 explosion in Harlem, and have shipped leaky portions of gas pipes to Washington, D.C., for further testing.

The National Transportation Safety Board has not officially determined what caused the blast. But the investigation apparently centers around leaks and cracks in the gas and water lines running beneath the buildings, according to a preliminary report released Monday.

Eight people died and more than 48 were injured when two buildings on Park Avenue north of 116th Street were destroyed. Investigators are also examining the maintenance records of the Con Edison pipes that supplied the buildings.

(Ben Wolford)