"All I saw was our lunch tent was smashed," Michael Gabriel told KTRK.
Roznowski said he could not confirm if the tent was used for meals, breaks or to stage equipment being used in the overhaul.
The crane collapse in Houston was the deadliest U.S. crude oil refinery accident since a 2005 explosion at BP's giant refinery in Texas City, Texas, killed 15 workers and injured 180 other people. Texas City is located 50 miles south of Houston.
Following a two-year investigation of the BP blast, the federal Chemical Safety Board recommended refiners not place workers in structures near process units incapable of withstanding catastrophic explosions.
All of the workers killed at BP Texas City were in temporary work trailers near the site of the explosion.
The fatalities in Houston follow two recent deadly crane collapses in New York. In May, two people were killed on Manhattan's Upper East Side after a large crane fell and damaged an apartment building. In March, seven were killed after a crane crushed a residential building.
Roecker declined to disclose the names of those killed and the companies for which they worked, pending notification of the next of kin.
He said the crane was owned by Deep South Crane & Rigging, which is based in Baton Rouge, Louisiana.
Deep South said in a statement it had few details about the accident.
"Our thoughts and prayers are with our employees and their loved ones," the company said.
Deep South is providing crane equipment to a number of large U.S. refinery projects, including expansions at the Motiva refinery in Port Arthur, Texas; the Marathon refinery at Garyville, Louisiana; and maintenance projects at Citgo's Corpus Christi, Texas, refinery and the ExxonMobil refinery in Joliet, Illinois.
Those killed and those injured worked for outside contractors preparing a seven-week overhaul of one of two coking units and one of two crude distillation units at the refinery located along the Houston Ship Channel, Lyondell said. The work began in early July.
A crude distillation unit does the initial refining of crude oil and a coker strains the last refinable material from crude oil.
LyondellBasell is a Netherlands-based chemical and refining company with annual revenues of $45 billion and 16,000 employees worldwide.
