Federal investigators are looking into the deadly collapse of one of the nation's largest mobile cranes at a Houston refinery.
The accident killed four workers and injured seven others yesterday.
It's the latest in a string of fatal accidents involving
cranes.

Refinery and crane company officials say investigators with the
Occupational Safety and Health Administration were at the site.
Baton Rouge, La.-based Deep South Crane & Rigging owns the
300 foot tall piece of equipment.
Company spokeswoman sayd Deep South plans to work with federal investigators.

The crane hit the ground with enough force to lift a worker off
the ground at a LyondellBasell refinery in southeast Houston.
The Houston Fire Department says three of the injured were
treated and released at the scene.
Two severely injured workers were taken by helicopter to Memorial Hermann-Texas Medical Center hospital.
LyondellBasell says their injuries were not life threatening.
Two other injured workers also were taken to a hospital and have
since been released.